For the efficient production of lysophospholipid the hydrolysis of phospholipid using phospholipase A, from Serratia sp. MK1 was studied in an aqueous-solvent, a two-phase and an emulsion system. Judged on the basis of productivity and the degree of hydrolysis, the yield of lysophospholipid in a two-phase system was found to be better than that obtained in an emulsion system. Among the 13 organic solvents tested phospholipase A, showed the most efficient catalytic activity and stability in butyl acetate. When 20% phospholipid was used it was completely hydrolyzed in this two-phase system.