This study examined effects of widowhood and marital harmony on health, health service use, and health care costs. The Americans Changing Lives data set contains 694 subjects who remained married and 61 subjects who became widowed between 1986 and 1989. Estimated annual mean 1989 health costs, adjusting for 1986 costs, age, sex, socioeconomic status, mental/physical health, 1989 health insurance, and selection biases are: $2,384 for widowed, $1,498 for married subjects. Adjusted annual 1989 estimates are: $2,766 for those widowed after harmonious marriages; $2,100 for those widowed after discordant marriages; $1,790 for spouses in discordant marriages; $1,228 for spouses in harmonious marriages. Harmonious marriages appear protective until widowhood, after which higher health costs result.