To the Editor.— Neonatal hepatitis has been vigorously investigated, but to date the results have been confusing and contradictory.1-6 The question of transplacental transmission is still unsettled.2 Stokes et al transmitted hepatitis to human volunteers from the serum of a 9-month-old infant who seven months earlier had had hepatitis.3 Blood from the infant's mother, although she had no history or hepatitis, was also shown to be capable of transmitting hepatitis to volunteers. The recent discovery of Australia antigen, which appears to be associated with serum hepatitis, provides a valuable tool for another investigation of this problem. Two studies are reported in which this had been attempted.7,8 In the first report, although Australia antigen was still present in the mother's serum at time of delivery, 17 months after hepatitis, cord blood failed to show evidence of antigen by the Ouchterlony method. In the second study there were