An open, pragmatic, phase IV clinical trial was undertaken to measure tolerance and assess the effectiveness of Antivipmyn® Africa, antivenom composed of lyophilized F(ab')(2) fragments of immunoglobulin G in field conditions. The study was conducted at the Institut Pasteur of Guinea (IPG) from August 2009 to February 2010. Two hundred twenty-eight victims of snakebites presented at the processing center of the IPG during this period, including one hundred fifty (65.8%) envenomations, mostly young men. One hundred twenty-four of them (82.7%) suffered from viper envenomations and 26 (17.3%) from elapid ones. All patients were treated by intravenous Antivipmyn® Africa, averaging 1.4 (± 1.0) vials, more in patients with neurotoxic envenomation than others (P < 10(-5)). Four patients (2.7%), showing cobralike envenomation, died shortly after their arrival at the IPG despite the administration of the antivenom. Ten patients showed mild side effects (rash or pruritus), out of which 5 (3.3%) were probably due to treatment. This study confirms the efficacy and safety of Antivipmyn® Africa.