BACKGROUND: This study examined the effects of marital status over two and three generations on last generation's mortality, and tested the hypothesis of an effect of the latest status (proximity effect) as well as the hypothesis of an accumulative effect. METHODS: The study population covers a random sample of all boys born in the the metropolitan area of Copenhagen with complete data from interviews and registers on two and three generation's marital status, socioeconomic position variables, and last generation's admission to psychiatric hospital, n = 2614. Among these 105 deaths occurred. Cox proportional hazards regression models were used to estimate the effect of marital status on mortality. RESULTS: Never married sons showed a considerably increased mortality compared with their married counterparts in the adjusted analyses. Mother's marital status at childbirth was also associated with increased mortality among the sons. There was no independent effect of maternal grandparent's experience of divorce on third generation's mortality. Son's marital status was the strongest marital status predictor of mortality. Accumulation of both two and three generations' marital status was significantly associated with mortality risk in a dose-response pattern. All analyses were adjusted for socioeconomic position variables and mental health. CONCLUSIONS: These results support the proximity hypothesis as son's marital status was the strongest predictor of mortality, and suggest an accumulative effect as each of the three non-married generations added to an increased mortality risk.