An aseptic meningitis epidemic occurred in Richmond, Va, in 1970. Eighty diagnosed cases occurred between June 19 and Oct 11. Echovirus type 3 was isolated from 17 of the patients. The epidemic was centered in eastern Richmond, a predominantly Negro lower socioeconomic area. The highest attack rate was for children under 6 months of age, and two thirds of the cases occurred in children under 5 years of age. The clinical attack rate for household contacts was only 3%. However, serum neutralization results suggest that siblings and parents may have transmitted the virus. Neither the origin of the epidemic nor a common place of exposure was found. Echovirus type 3, which had not previously been isolated in Virginia and had been uncommon in the United States, became the most frequently isolated enterovirus in the United States in 1970.