This book constitutes the refereed proceedings of the Second International Symposium on Medical Data Analysis, ISMDD 2001, held in Madrid, Spain, in October 2001. The 43 revised papers presented together with three invited keynote papers were carefully reviewed and selected from 72 submissions. Among the issues addressed are data analysis and diagnosis, classification, clustering, medical image analysis, Bayesian networks, decision support systems, fuzzy modeling, time series analysis, collaborative filtering, pattern recognition, case-based reasoning, rule-based inference, and computer vision.