Differences in mortality according to marital status and sex in early-age death among U.S. professionals are examined. "A reversal of the sex differential in mortality appears in the 1968-72 death rates of white Wisconsin professionals.... Substantially more professional women were not married, and this differential in the distribution of marital status accounted for 37.8 per cent of the women's deaths. The results linking marital status and mortality are discussed in terms of Durkheim's concepts of social integration and anomie, and are related to recent empirical studies connecting marriage and parenthood with health and mortality. Part II will further analyse the data in terms of cause of death and occupational variables."