The development of a new diagnostic procedure for the identification of Venezuelan, eastern and western equine encephalomyelitis (VEE, EEE, WEE) viruses is described. The procedure utilizes virus precipitation with reference fluorescein-conjugated gamma globulin, followed by cellulose acetate electrophoresis. Clinical specimens containing varying concentrations of virus yielded, in primary duck embryo cell culture, sufficient virus for detection within 22 to 44 hours. Identification of VEE, EEE and WEE virus in specimens was accomplished by microprecipitation within this time. In contrast to conventional identification methods, our procedure eliminates the costs of utilizing laboratory animals and considerably reduces the time required for virus identification.