Prophylactic and therapeutic effect of two oils had been carried out either prior to infection or postinfection respectively in rats. Each rat in either case was orally administered with N. sativa oil or A. cepa oil in a dose 5 mg/kg body weight/day for 2 weeks. Assessment of results was by: (1) adult worm count in the intestine on 7th and 20th day post infection. (2) larval count in the muscles on the 60th day post infection. (3) Index of reproductive capacity. (4) Detection of antibodies against T. spiralis larvae by using ELISA. The results showed that, N. sativa oil as prophylactic treatment prior to T. spiralis infection is more effective than A. cepa oil on both adult worms and muscle larval count. While, A. cepa oil was showed more effectiveness than N. sativa on decline number of adult worms and muscle larvae when used as therapeutic treatment post infection. The level of antibody was recorded early in the groups that treated with N. sativa oil. In conclusion, N. sativa and A. cepa oils have anthelmintic effect in the rats infected with T. spiralis infection and increased the production of antibodies generated during life cycle of this parasite.