Cambendazole was used for the treatment of strongyloidiasis in 40 hospitalized patients, given in a single dose of 5 mg/kg body weight. According to the criteria adopted, parasitological cure was obtained in 100% of cases. Side effects were negligible, and did not require interruption of treatment. We therefore conclude that cambendazole is at present the most effective agent for the therapy of human strongyloidiasis.