A multivalent coral snake antivenin was prepared in horses immunized with a mixture of venoms from the species Micrurus nigrocinctus, M. mipartitus, and M. frontalis, following immunization procedures previously reported (2). Plasma from the horses was fractionated with ammonium sulfate. The antivenin produced was then tested against venoms from ten species. The neutralization titers obtained indicate it would be useful in treating bites received from most of the important coral snake species in North and South America, namely: M. fulvius, M. alleni, M. carinicaudus dumerilii, M. corallinus, M. frontalis, M. lemniscatus, M. mipartitus, M. nigrocinctus, and M. spixii. The authors note that appropriate cooperation by scientists in various countries would make production of this antivenin an easy matter, and that the product could conveniently be distributed via PAHO or other international agencies. They also note that the antivenin showed no significant neutralizing effect against M. surinamensis venom. This situation would appear to justify preparing a monovalent antivenin against M. surinamensis, or else including M. surinamensis venom in an immunization formula for a multivalent antidote.