During the past decades, there have been some significant improvements in risk analysis applied to petroleum exploration and production. This special issue is dedicated to show some contributions and developments of risk analysis applied to petroleum exploration, field appraisal and development, production forecast under uncertainty, decision-making process, portfolio management, and real options approach. A brief overview is presented in this paper in order to introduce the universe of risk analysis, followed by a summary of the main contributions for this special edition and discussion and implication of the main trends in risk analysis. © 2004 Elsevier B.V. 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