Twenty-one strains of Venezuelan encephalitis (VE) virus isolated from three habitats in Trinidad, W.I. during 1960 to 1972, were subtype III (Mucambo) VE virus by plaque-reduction neutralization tests. Like prototype Mucambo virus, each strain killed 8- to 15-week-old mice inoculated intraperitoneally. If the subtype I strain of VE virus that caused a major outbreak in Trinidad during 1943 to 1944 persisted on the island into the 1960s and early 1970s, it did not become the dominant VE virus in these three enzootic foci.