IN A PREVIOUS study1 evidence was presented which indicated that death of the mother during childhood was more likely to be related to subsequent psychosis than death of the father. The incidence of maternal deaths was three times as great among psychotic persons as among normal controls (15.7 versus 5.3 per cent); the incidence of paternal deaths, on the other hand, was approximately equal among the psychotic and the normal persons (11.1 and 10.0 per cent). The ratio of maternal to paternal deaths is a useful measure, since mortality rates vary widely both from decade to decade and according to social and economic status in any given year. Thus, in the general population the normal expectancy is that two fathers will die for every mother that dies. The reason for the preponderance of paternal deaths is that mortality rates are higher for males than for females at all ages