Poly(L-malic acid), PM, production by the non-growing cells of Aureobasidium sp. strain A-91 was investigated. Reaction conditions were optimized using non-growing cells of strain A-91. The addition of CuSO4 to the cell preparation medium was found to be effective to prepare active cells for PM production. The nongrowing cells of the strain yielded 80.0 g/l PM during 5 days’ incubation at 30 degrees C under optimal conditions (160 g/l glucose and 40 g/l CaCO3).