In a multiclinic trial in Brazzaville, Congo, 14 patients with late-stage Trypanosoma brucei gambiense trypanosomiasis were treated with eflornithine. All cases had previously been treated with one or several courses of melarsoprol. Eflornithine treatment consisted of 400 mg/kg/day intravenously for 14 days followed by 300 mg/kg/day orally for 21 days. After treatment all patients had a disappearance of trypanosomes from cerebrospinal fluid (CSF), a normalization of CSF WBC count, and, where present prior to study, a clear, rapid and lasting amelioration of neurological signs. Neither clinical nor biological adverse effects necessitated modifying or discontinuing treatment. These encouraging results in melarsoprol-refractory cases demonstrate, despite certain logistical problems, the interest of eflornithine in the treatment of human African trypanosomiasis.