Throughout 1981 and 1982 all deaths of infants aged 8-365 days (post-perinatal infant mortality, PPIM) in Scotland were studied. During this period there were 135 250 live births and 1533 infant deaths (infant mortality rate 11.3), including 763 PPIM deaths (5.6 per 1000 live births). These 763 deaths fell into three main categories: birth-determined (329), accident or acquired disease (65), and cot deaths (369). Birth-determined deaths included 109 preterm, 199 congenital disorders, and 21 miscellaneous deaths. 61 of the cot deaths were fully explained on necropsy, in 141 an associated finding which might or might not be relevant was found, and in the remaining 167 no explanation was found. The cot death rate was 2.7 per 1000 live births overall (3.3 for boys, 2.1 for girls), and more second-born than first-born children died (approximately 3:2). Excluding "explained" cot deaths the rate was 2.3 per 1000 live births.