A total of 4,486 widowers of 55 years of age and older have been followed up for nine years since the death of their wives in 1957. Of these 213 died during the first six months of bereavement, 40% above the expected rate for married men of the same age. Thereafter the mortality rate fell gradually to that of married men and remained at about the same leveLThe greatest increase in mortality during the first six months was found in the widowers dying from coronary thrombosis and other arteriosclerotic and degenerative heart disease. There was also evidence of a true increase in mortality from other diseases, though the numbers in individual categories were too small for statistical analysis.In the first six months 22.5% of the deaths were from the same diagnostic group as the wife's death. Some evidence suggests that this may be a larger proportion than would be expected by chance association, but there is no evidence suggesting that the proportion is any different among widows and widowers who have been bereaved for more than six months.