During an investigation of the effect of maternal pelvic irradiation on the health and development of subsequent children, several interesting and vitally important observations have been made, as reported in earlier papers.1The most significant conclusion reached is that pelvic radiotherapy during pregnancy is extremely injurious to the fetus. Severe disturbances of the central nervous system were observed to be of common occurrence among children irradiated in utero. Thus, of seventy-five children so exposed, twenty (26.6 per cent) exhibited marked defects, eighteen (24 per cent) being microcephalic idiots. Since the completion of these studies, attention has been directed to a report of another microcephalic child who also had been irradiated in utero.2The present paper deals with these nineteen microcephalic children, and particularly stresses the ocular defects. In a previous paper, a survey was made of the factors possibly responsible for the ill health of thirty-eight children irradiated