Four new metabolites, botcinins A-D (1-4), were isolated from the culture filtrate of a strain of Botrytis cinerea. Their structures were determined by spectroscopic methods, mainly NMR techniques, molecular modeling, and the modified Mosher's method. They exhibited antifungal activities against Magnaporthe grisea, a pathogen of rice blast disease. Botcinins B and C have a MIC of 12.5 mu M, and botcinins A and D are not active below 100 mu M.