A baby girl, with a birth weight of 2540 g, developed myocarditis with gross, permanent myocardial calcification. The clinical course was progressively downhill, and she died at 14 months of age. Neutralisation antibody to Coxsackie virus group B1 rose from 1:80 after delivery to 1:1280 at age 5 months. The protracted course of this infant's disease represents a new clinical form of fatal neonatal Coxsackie virus group B infection.