While limited data suggest significant gender differences in mental and physical health risks following marital disruption, men have not been studied as intensively as women. In this study, self-report data and blood samples were obtained from 32 separated or divorced men and 32 sociodemographically matched married men. Separated/divorced men were more distressed and lonelier, and reported significantly more recent illness than did married men; the former also had significantly poorer values on two functional indices of immunity (antibody titers to two herpesviruses), while not differing significantly on quantitative indices (percentages of helper and suppressor cells and their ratio). Among married men, poorer marital quality was associated with greater distress and a poorer response on one functional immunological measure, antibody to Epstein-Barr virus (EBV), as well as lower helper/suppressor ratios. Among separated/divorced subjects, those who had separated within the past year and who had initiated the separation were less distressed, reported better health, and had a better performance on one functional immunological assay (EBV antibody titers) than did noninitiators. These data are discussed in the context of research on longer-term adaptation to marital disruption.