Various stages of the infection process among B. cinerea strains isolated from tomatoes or grapes, belonging to different genetic groups, were compared. It was found that strains of B. cinerea isolated from either grapes or tomatoes showed differences in adhesion patterns and in the percentage of germination on tomato cutin. In strains isolated from tomato the first stage of adhesion occurred faster than in strains isolated from grape. At the same time strains isolated from tomato showed a higher percentage of germination on tomato cutin than the other strains after 9 h of incubation. The production and isoenzymatic patterns of polygalacturonases, pectin methyl esterases, pectin lyases, p-nitrophenylbutyrate esterases and laccases by B. cinerea in solid-state fermentation also were analyzed. Correlation between the production of these enzymes and the origin of the strains was not found. On the other hand all strains produced different isoenzymes and a common pattern between the strains was not observed. The ability of B. cinerea strains to colonize tomato leaves also differs between the isolated strains obtained from grapes and tomato. Strains isolated from tomato were more virulent on tomato leaves than strains isolated from grapes.