Four new metabolites, botcinins A-D, 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 Magnaporthegrisea, a pathogen of rice blast disease. Botcinins B and C have a MIC of 12.5 microM, and botcinins A and D are not active below 100 microM.