The steroidal glycoalkaloid α-tomatine of tomato plants has been reported to protect Lycopersicon species against fungal attack. Two isolates from Fusarium solani were found to produce an extracellular enzyme inducible by α-tomatine. TLC showed that the enzyme catalyzes the hydrolysis of the glycoalkaloid into β-lycotetraose and tomatidine. The enzymatic activity was concentrated against polyethylene glycol 35000, and the enzyme was partially purified by preparative isoelectric focusing, preparative gel electrophoresis and ion-exchange chromatography. The enzyme was found to be a monomer of about 32 kDa by both SDS-PAGE and gel filtration. This molecular mass differs from that of the tomatinase of Fusarium oxysporum (50 kDa). Moreover, polyclonal antibody anti- tomatinase of F. oxysporum f. sp. lycopersici did not recognize the tomatinase from F. solani, suggesting that this tomatinase may be a novel enzyme.