Corn starch,either acidic or enzymatically hydrolyzed,were used as substrates for itaconic acid production by Aspergillus terreus At394.The degree of hydrolysis had a great influence on itaconic acid production and the results showed that it was suitable when corn starch was sacchari-fied at 35% DE(dextrose equivalent).The medium composition was(g/L) 100 starch hydrolysate,3 NH4NO3,4 MgSO4.7H2O,2 corn steep liquor,0.2 KH2PO4 and pH 3.0.When the optimal conditions were applied in shaking flasks,the itaconic acid production was 54.1 g/L with a yield of 59.2 %.