This book constitutes the refereed proceedings of the 15th Annual Symposium on Combinatorial Pattern Matching, CPM 2004, held in Istanbul, Turkey in July 2004. The 36 revised full papers presented were carefully reviewed and selected from 79 submissions. The papers are devoted to current theoretical and computational aspects of searching and matching of strings and more complicate patterns, such as trees, regular expressions, graphs, point sets, and arrays. Among the application fields addressed are computational biology, bioinformatics, genomics, proteinomics, the web, data compression, coding, multimedia, information retrieval, data analysis, pattern recognition, and computer vision.