It has long been recognized that the acute forms of leukemia are far more common in children than in adults and that younger children are more frequently affected than older ones. In the third decade acute leukemia occurs far less than in the second, and, after the age of 30 years, it is relatively rare as compared with earlier ages. In the acute forms of the disease as well as the chronic types seen in adults, males are more commonly affected than females, the figures showing from 60 to 79 per cent of males in various groups reported. There are no statistics available which warrant more than the foregoing general statements, since all reports have dealt with relatively small groups of 100 cases or less. The only series of sufficient size to allow an age incidence analysis was that reported by Ward,1 who collected 729 cases of all varieties of