Our aim was to assess the increase in amylase production in a novel submerged-culture system (involving co-culture of filamentous fungi) and the effect of medium composition on the amylolytic activity. Filamentous fungi, Aspergillus oryzae (HI-G strain) and Rhizopus arrhizus (P20 strain) were used as α-amylase and glucoamylase-producing organisms, respectively. The initial concentration of nitrogen and carbon sources, and the ratio of spores to mycelial weight of A. oryzae and R. arrhizus were found to influence the activity of amylolytic enzymes. Maxim enzymatic activity was achieved when initial maltose and ammonium acetate concentrations were 3％ and 1.29％ (w/v), respectively. Under these cultivation conditions, the cell concentration was 0.62 g per 100 mL, and glucoamylase and α-amylase activities were 675 and 4.68 U/mL, respectively. In addition, agitation speeds (50, 125, 200, 275, 350, and 500 rpm) in a 5-L jar fermenter af fected the enzyme activity; an increase in glucoamylase production was obtained at 200 rpm after 120 h. These results indicate that high production of glucoamylase and α-amylase can be attained in a system of submerged co-culture of A. oryzae and R. arrhizus.