The influence of two water miscible solvents (ethanol and isopropanol) on the activity of Bacillus amyloliquefaciens alpha -amylase was studied. In ethanol-aqueous buffer (1:4, v/v) retained about 60% of the activity shown in water alone, both after 1 h hydrolysis. Isopropanol - aqueous buffer (1 : 4,v/v) reduced the activity at 40%. The amount and the quality of produced oligosaccharides were effected by ethanol and isopropanol presence. In the mixture of produced oligosaccharides formed in the presence of the solvents only DP2, DP3 and DP6 were found. The disappearance of DP4, DP5 and DP7 which were formed in aqueous buffer suggest that a change in substrate affinity at the active centre is induced in the ethanol or isopropanol presence in buffer.