An antigenic variant of E 11 was the most frequently encountered echovirus in the United States in 1979. Several reports have indicated that infection with this agent was often associated with an overwhelming clinical course in neonates. Our case was in a 5-week-old infant with an E 11 infection complicated by subacute salicylate intoxication. This unfavorable combination resulted in a fulminant and fatal illness simulating Reye's syndrome.