Inclusion complex of omeprazol with β-cyclodextrin and hydroxypropyl-β-cyclodextrin were prepared by coprecipitation and freeze-drying method respectively. Effects of these inclusion complex on RBCs were monitored with a spectrophotometer by the method of Kahan et al. and the mutagenic activity based on the Ames plate incorporation test in the presence and absence of liver microsomal enzyme(S9 fraction) using Salmonella typhimurium TA98 and TA100. The RBCs hemolysis and mutagenic activity of these complex were not detected.