Albendazole and mebendazole were comparatively evaluated in 22 adult patients for their in vivo effects on hookworm eggs. Both drugs were given 200mg twice daily for three consecutive days. Stool specimens wore collected before treatment and during the following five days. The Stool egg count was carried out by Stolls method and each specimen was also cultured by Hara-da-Mori technique for at least eight days. The mean pre-treatment percentage of incubated hookworm eggs that developed to larvae was 75.3% in albendazole group and 68.8% in mebendazole group respectively. One day following the initiation of treatment the mean percentage was remarkably reduced to 0.25% in albeadaole group and no eggs developed to larval stage beyond day 1. 0ne day and two days following the initiation of treatment the mean percentage was 16.23% and 23.13% respectively in mebendazole group. No eggs developed to larval stage on day 3 and thereafter. Albendazole seems to have better ovicidal effect than mebendazole.Albendazole and mebendazole were also comparatively evaluated in 123 adult patients with single or mixed infections of hookworm, ascarisis, and trichuris. A single dose of 400mg was used for both drugs. 2 and 4 weeks after treatment, their stools were examined by brine flotation technique. The hookworm eggs negative conversion ratss 2 weeks after treatment were 78.8% and 26.4% respectively in albeadazole and mebendazole group; while those 4 weeks after treatment were 74.1% and 25.5% respectivley. For ascariasis, the eggs negative conversion rates were 98.0% and 92.0% respectively. For trichuriasis, the negative conversion rates were only 20.6% and 27.7% respectively