An epidemic of echovirus 11 infections occurred in the Cambridge special-care baby unit during August to October, 1982. There were 21 confirmed infections in babies; 1 died, 1 recovered after resection of a kidney, 5 had meningitis, and 6 had respiratory symptoms. Normal human immunoglobulin which contained antibody to echovirus 11 was administered intramuscularly (250 mg) to give protection. None of the children given immunoglobulin immediately after delivery (205 doses) developed symptoms or ill-effects. Serological studies reinforced earlier evidence for the protective action of antibody, and it is considered that immunoglobulin is a valuable safeguard for exposed newborn infants.