Three groups, each of 10 rats were experimentally infected with Trichinella spiralis larvae (250/rat). On the 5th week postinfection animals of two groups were treated with a single dose of Synanthic (Oxfendazole) and Ivomec MK-933 at a dose of 5 mg and 0.2 mg/kg B. W. respectively. Efficacy rate of the former was 84.2% and for the later was 73.5% depending on the number of living larvae in the diaphragm. Anti-Trichinella spiralis haemagglutinating antibodies were monitored before and after treatment. They were markedly declined two weeks after treatment. This makes passive haemagglutination test a feasible test to evaluate the drug efficacies either in laboratory or field studies.