Paromomycin sulfate, an antibiotic not appreciably absorbed from the gastro-intestinal tract and used previously mainly for intestinal amebiasis and against intestinal bacteria, was used in this investigation for treating 30 Taenia infections and three cases of Hymenolepis infection. The dosage used was 40 mg per kg per day for 5 days in half of the cases, and as a single dose of 75 mg per kg, with a maximum of 4 g, in the rest. The patients were followed for 3 to 4 months, and it was found that only two remained infected (93.3% cure rate). Side-effects appeared in 50% of the cases, diarrhea and abdominal pain being the most frequent complaints. These adverse effects appeared more frequently in the patients treated for several days. It was concluded that paromomycin is effective for treating infection with Taenia solium and Taenia saginata at the dosages used, although it causes frequent, but not severe, side-effects.