A study to establish the prevalence of intestinal helminthiases among schoolchildren of riverine communities in the Ilaje-Ese Odo Local Government Area of Ondo State, Nigeria was conducted. Ninety-four percent of the children studied were infected with intestinal helminths. Trichuris trichiura infection was the commonest (84%), followed by Ascaris lumbricoides (75.3 %) and hookworm (7.6 %). Dual helminthic infections were recorded, with Ascaris-Trichuris having the highest prevalence among the children. Poor environmental sanitation and personal hygiene combined with the absence of potable water and a lack of awareness of the effects of nematode infection were identified as the possible reasons for the high rate of infection. Treatment with albendazole (200 mg) brought about reductions in the level of Trichuris trichiura (to 41.7%), Ascaris lumbricoides (to 4.2%) and Hookworm (to 0.7%). The estimated rates of reduction were 94.4%, 49.7%, and 90.2% for Ascaris lumbricoides, Trichuris trichiura and hookworm respectively. Post-treatment helminthic reduction, as found in this study, is expected to enhance the mental and physical development of the children. Community mobilization with health education messages aimed at improving personal and community hygiene was initiated with an emphasis on creating a sustained reduction in the burden of helminthic infection.