A method has been developed for the purification of alliinase from garlic bulbs. High purity preparations of the enzyme were obtained with specific activity increased 67-fold over that of the homogenate. The preparations were homogeneous on electrophoresis in polyacril gel. Total activity yield was 25%. The native enzyme has a molecular weight of 130.000 and consists of two subunits. Approximately 6 moles of firmly bound pyridoxal phosphate are determined per 1 mole of the purest enzyme (4 equivalents are apparently bound non-specifically outside the active sites). The isoelectric point (pI) of alliinase in 6.2. The enzyme's absorption and circular dichroism spectra have one maximum at 430 nm, in the characteristic range of many pyridoxal-P-containing enzymes. The Km value for the natural substrate, alliin, is 5 . 10(-4) M.