Pacific Rim Mining Corp. Board of Directors Approves Adoption of Shareholder Rights Plan

Pacific Rim Mining Corp.'s (the "Company" or "Pacific Rim") (TSX: PMU) (AMEX: PMU) board of directors has approved the adoption of a Shareholder Rights Plan (the "Rights Plan"). Shareholder approval of the Rights Plan will be sought at the Company's annual general meeting of shareholders scheduled to be held on August 29, 2006. If the Rights Plan is ratified by the shareholders, the Rights Plan will have an initial term which expires at the annual general meeting of shareholders of the Company to be held in 2009, unless terminated earlier. The Rights Plan may be extended beyond 2009 by resolution of shareholders at such meeting. The Toronto Stock Exchange has accepted for filing the Rights Plan, subject to shareholder ratification.

The Rights Plan has been implemented by way of a rights plan agreement (the "Rights Plan Agreement") which has been designed to protect shareholders from unfair, abusive or coercive take-over strategies including the acquisition of control of the Company by a bidder in a transaction or series of transactions that may not treat all shareholders fairly nor afford all shareholders an equal opportunity to share in the premium paid upon an acquisition of control. The board of directors of the Company (the "Board") considers that the adoption of the Rights Plan is desirable and in the interests of all of the Company's shareholders. The Rights Plan Agreement was adopted to provide the Board with sufficient time, in the event of a public take-over bid or tender offer for the common shares of the Company, to pursue alternatives which could enhance shareholder value. These alternatives could involve the review of other take-over bids or offers from other interested parties to provide shareholders desiring to sell the Company's common shares with the best opportunity to realize the maximum sale price for their common shares. In addition, with sufficient time, the Board would be able to explore and, if feasible, advance alternatives to maximize share value through possible corporate reorganizations or restructuring. The directors need time in order to have any real ability to consider these alternatives.

Effective today, rights (the "Rights") will be issued and attached to all of Pacific Rim's outstanding common shares. A separate rights certificate will not be issued until such time as the Rights become exercisable (which is referred to as the "separation time"). The Rights will become exercisable only if a person, together with its affiliates, associates and joint actors, acquires or announces its intention to acquire beneficial ownership of Pacific Rim common shares which when aggregated with its current holdings total 20% or more of the outstanding Pacific Rim common shares (determined in the manner set out in the Rights Plan). The Rights will permit the holder to purchase common shares of the Company at a 50% discount to their market price (as defined in the Rights Plan Agreement).

The Rights will not, however, be triggered by a "Permitted Bid" which is defined as a bid which is outstanding for a minimum of 60 days, is made to all of the shareholders of the Company for all of their common shares and, subject to other specified conditions, is accepted by a majority of independent shareholders (as detailed in the Rights Plan).

The Company has no knowledge of any pending or threatened takeover bids for the Company, and has no reason to believe that any takeover offer for the Company's shares is imminent.

Additional details regarding the Rights Plan will be provided in the Management Information Circular that will be available for viewing on SEDAR and mailed to the shareholders of the Company prior to the Company's upcoming annual general meeting of shareholders.

About Pacific Rim Mining Corp.

Pacific Rim is a growth-oriented, revenue-generating, environmentally and socially responsible gold exploration company with operational and exploration assets in North, Central and South America. The Company is expanding and developing its advanced-stage, high grade, low cost El Dorado gold project in El Salvador and is actively exploring a pipeline of grassroots gold projects. Pacific Rim's goal is to become a low cost, intermediate level gold producer.

On behalf of the board of directors,

"Thomas C. Shrake"

Thomas C. Shrake
President and CEO

This document contains forward-looking statements concerning the Company's plans for its properties, operations and other matters. These statements relate to analyses and other information that are based on forecasts of future results, estimates of amounts not yet determinable and assumptions of management. Statements concerning estimates of mineral resources and reserves may also be deemed to constitute forward-looking statements to the extent that they involve estimates of the mineralization that will be encountered if the property is developed, and in the case of mineral reserves, such statements reflect the conclusion based on certain assumptions that the mineral deposit can be economically exploited. Any statements that express or involve discussions with respect to predictions, expectations, beliefs, plans, projections, objectives, assumptions or future events or performance are not statements of historical fact and may be "forward-looking statements". Forward-looking statements are subject to a variety of risks and uncertainties, which could cause actual events or results to differ from those reflected in the forward-looking statements, including, without limitation:

- risks related to gold price and other commodity price fluctuations;

- risks and uncertainties relating to the interpretation of drill results, the geology, grade and continuity of mineral deposits;

- risks related to the inherent uncertainty of production and cost estimates and the potential for unexpected costs and expenses;

- results of initial feasibility, prefeasibility and feasibility studies, and the possibility that future exploration, development or mining results will not be consistent with the Company's expectations;

- mining and development risks, including risks related to accidents, equipment breakdowns, labour disputes or other unanticipated difficulties with or interruptions in production;

- the potential for delays in exploration or development activities or the completion of feasibility studies;

- the uncertainty of profitability based upon the Company's history of losses;

- risks related to failure to obtain adequate financing on a timely basis and on acceptable terms;

- risks related to environmental regulation and liability;

- risks related to hedging activities;

- political and regulatory risks associated with mining and exploration; and

- other risks and uncertainties related to the Corporation's prospects, properties and business strategy.

Some of the important risks and uncertainties that could affect forward looking statements are described in the Company's regulatory filings, available on SEDAR (www.sedar.com). Should one or more of these risks and uncertainties materialize, or should underlying assumptions prove incorrect, actual results may vary materially from those described in forward looking statements. Forward looking statements are made based on management's beliefs, estimates and opinions on the date the statements are made and the Company undertakes no obligation to update forward-looking statements if these beliefs, estimates and opinions or other circumstances should change. Investors are cautioned against attributing undue certainty to forward-looking statements.

The TSX and the AMEX have neither reviewed nor accept responsibility for the adequacy or accuracy of this release.

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