The efficacy of mebendazole and pyrantel pamoate was studied in two groups of 59 and 58 cases, respectively, of patients with polyparasitosis. Mebendazole had a cure rate of 96%, 82.2%, 71.4% and 66.6% in A. lumbricoides, hookworm, T. trichiura and S. stercoralis, respectively, while the corresponding figures for pyrantel pamoate were 92.6%, 85.7%, 19.4% and 0%. Pyrantel pamoate is considered to have no significant effect on T. trichiura and S. stercoralis. None of the drugs had any effect on T. saginata. Both drugs have been found to be equally effective against enterobiasis by various authors. It is recommended that pyrantel pamoate be the drug of choice in cases of multiple parasitic infections excluding T. trichiura and S. stercoralis whereas those with one or both of these in addition to others should be treated with mebendazole. Mebendazole can be prescribed for patients with clinical evidence of helminthic infections even where stool examination is not possible as it covers almost the whole range of common helminthic infections. The only limitation for poorer patients however is its cost. Pyrantel pamoate has a wider applicability for the poorer patients in spite of the fact that it is ineffective against trichurids and S. stercoralis.