We compared the α-amylase activity in rice grains of nonglutinous to that of glutinous varieties. No significant difference was seen in this activity of brown rice between nonglutinous and glutinous varieties harvested in different areas and years. No significant difference was either seen in α-amylase activity of brown rice between nonglutinous varieties and their glutinous mutants. The maximum brown rice paste viscosity of the glutinous mutants determined using a Rapid Visco Analyzer was, however, lower than that of the nonglutinous varieries. Alpha-amylase activity correlated negatively with the maximum viscosity but regression lines for the glutinous mutants and the nonglutinous varieties differed. The maximum starch paste viscosity in the glutinous mutants was lower than that in the nonglutinous varieries. The ratio of maximum viscosity in starch paste added with α-amylase to that without α-amylase was lower for the glutinous mutants than for the nonglutinous varieries. These results indicate that with regard to brown rice a reason for lower maximum viscosity in glutinous than in nonglutinous rice paste was the greater effect of α-amylase activity on the maximum viscosity of glutinous rice paste, not the higher α-amylase activity in glutinous rice grains.