A combined syrup preparation of pyrantel pamoate and oxantel pamoate containing 50mg/ml of respective anthelminthics was evaluated on the efficacy to treat the human intestinal nematodes. Total 24 cases were treated with oral administration of above preparation 10 mg/kg body weight by single dose. The results were summarized as follows: 1. Out of 21 cases of Ascaris lumbricoides infection, 19 (90.5%) turned to be egg negative on 21 days after treatment and egg-reduction rate was 99.7%. 2. 17 cases out of 19 cases infected with Trichocephalus trichiurus were egg negative after treatment (84.2%) and egg reduction rate was 60.6%. 3. As for Ancylostoma duodenale infection, egg negative conversion rate was 88.9% and egg reduction rate was 98.1% by single oral administration among 9 infected cases. 4. In Enterobius vermicularis infection, all of 17 cases gave negative anal swab on 21th day after the treatment. From the above results, it was assumed that the anthelminthic activities of pyrantel pamoate and oxantel pamoate were not potentiated by the mixture of two kinds of drugs but showed simple additive effect.