Extraction of alkaline phosphatase (AP) from the tissues of small intestines of mice experimentally infected with the Egyptian strain of S. mansoni before and after oltipraz treatment was carried out. The drug was given in a single oral dose of 500 mg/kg body weight. The results obtained revealed that the drug led to significant reduction in the AP mean level after 30 and 60 days from therapy in comparison to the infected untreated controls. Oltipraz also caused significant reduction in the intestinal AP mean level of the drug control group of mice after 5 and 20 days from drug administration in comparison to normal controls, which might be attributed to the toxic effect of the drug on the intestinal cells.