A matched case-control study on clinical symptoms of Hymenolepis nana and an open trial of nitazoxanide treatment were conducted in a village on the northern coast of Peru. Interview data were obtained from 25 individuals with hymenolepiasis only and 46 matched controls. Individuals with other intestinal helminths or giardiasis were excluded. Twenty nitazoxanide-treated cases were followed with stool examination a month later. There were no significant differences between groups in the prevalence of symptoms except headache, which was less frequent in the cases. Treatment efficacy was 75%. Hymenolepiasis in this community did not have significant impact on specific symptoms.