One hundred autopsy reports of persons who died in Iceland aged 90 years or over were studied and the causes of death were recorded. Another 100 autopsy reports of persons aged 70 years and under were used as controls. The disease pattern of those aged 70 or under did not differ much from that appearing in the Icelandic National Mortality Statistics, all ages included. However, in those aged 90 and over, the number of important diseases was higher and pneumonia, in particular, occurred more frequently both as an intervening and as an underlying cause of death. In the older age group, dementia was 3.4 times more common in males and 4.7 times more common in females. Malignant neoplasms were less frequent as causes of death in the older age group. In the older age group there was a much lower frequency of myocardial infarction compared with the controls, although the degree of arteriosclerosis did not differ in these two groups.