Aspergillus oryzae produced a small amount of lipase (0.05-0.8 U/wet-g of solid medium) in solid cultures, in contrast to the larger amount (0.46 U/ml) in a shake-flask culture in a modified GYP medium containing 2% glucose, 1% yeast extract and 2% Polypepton. Optimum conditions of lipase production in the submerged culture of A. oryzae were determined in terms of pH, composition of medium, and temperature. In a shake-flask culture at 28-degrees-C, the maximum amount of lipase increased to 0.78 U/ml upon the addition of 3% soybean oil to the modified GYP medium. In a jar fermentor culture, 30 U/ml lipase activity was obtained after 72 h at 28-degrees-C under appropriate conditions. Lipase production was greatly influenced by the culture temperature, and the optimum temperature for lipase production was about 24-degrees-C with a narrow temperature range, which was 10. degrees lower than that for the growth. In the submerged cultures, two kinds of lipase at least exhibiting different substrate specificities were also suggested.