The 15th Annual Symposium on Combinatorial Pattern Matching was held in Ciragan Palace Hotel, Istanbul, Turkey during July 5 7, 2004. CPM 2004 - peated the success of its predecessors; it even surpassed them in terms of the numberofinvitedspeakers, thenumberofsubmissions, andthenumberofpapers accepted and presented at the conference. In response to the call for papers, CPM 2004 received a record number of 79 high-quality submissions. Each submission was reviewed by at least three program committee members and the comments were returned to the authors. Following an extensive electronic discussion period, the Program Committee accepted36ofthesubmissionstobepresentedattheconference.Theyconstitute originalresearchcontributionsincombinatorialpatternmatchingalgorithmsand datastructures, molecularsequenceanalysis, phylogenetictreeconstruction, and RNA and protein structure analysis and prediction. CPM 2004 had ?ve invited speakers. In alphabetical order they were: Evan Eichler from the University of Washington, USA, Martin Farach-Colton from Rutgers University, USA, Paolo Ferragina from the University of Pisa, Italy, Piotr Indyk from MIT, USA, and Gene Myers from the University of California, Berkeley, USA. It is impossible to organize such a successful program without the help of many individuals. We would like to express our appreciation to the authors of the submitted papers and to the program committee members and external referees, who provided timely and signi?cant reviews. July 2004 S.C. Sahinalp, S. Muthukrishnan, U. Dogrusoz Organization CPM 2004 was locally organized by Bilkent University, Ankara, Turkey. Within Bilkent University, the Center for Bioinformatics (BCBI) and the Computer Engineering Department cooperate