A comparative bioavailability study was carried out on two enteric-coated capsules (20 mg each) of omeprazole (omeprazole, Alembic: "A" and Losec, Astra, England: "B"). The in-vitro dissolution of both products "A" and "B" met the prescribed USP standard. The bioavailability of single dose (20 mg) and multiple doses (20 mg once daily for 7 days) of both products "A" and "B" were carried out in eight healthy male volunteers in a crossover design. The rate and extent of bioavailability of omeprazole was higher in product "A" following a single oral dose, suggesting its therapeutic advantage over the product "B" in the prevention of acid aspiration during surgery. In multiple dose study, the two products were found bioequivalent as assessed by AUC0-infinity, Cmax, tmax and t1/2 elimination.