This book constitutes the refereed proceedings of the 8th International Conference on Case-Based Reasoning, ICCBR 2009, held in Seattle, WA, USA, in July 2009. The 17 revised full papers and 17 revised poster papers presented together with 2 invited talks were carefully reviewed and selected from 55 submissions. Covering a wide range of CBR topics of interest both to practitioners and researchers, the papers are devoted to theoretical/methodological as well as to applicative aspects of current CBR analysis.