The relationship between the number of persons per room in the home and the relative occurrence of stress-related morbidities of hospitalized patients is investigated. The social factors of age, social class, and level of social support also are examined as they relate to both density and morbidity type occurrence. The population under study is composed of all Kaiser-Permanente Medical Care Program members twenty years of age and older, discharged from Bess Kaiser Hospital during 1974, and whose diagnosed morbidity was included in specific morbidity categories. All data were obtained through the facilities of the Health Services Research Center, Kaiser Foundation Hospital, Portland, Oregon. The data are largely ordinal in nature, and are presented in the form of contingency tables, utilizing chi square and Tau B as measures of degree of association and strength of relationship. An interval level of measurement is obtained through dichotomization of the variables and the derivation of Pearsonian correlation coefficients, and regression coefficients which are utilized in path analysis. The findings indicate that higher residential population density is related to disproportionate occurrence of some, but not all, stress-related morbidities, and that some stress-related morbidities are associated with low population density. However, in comparing stress-related morbidities with non-stress related morbidities, it is found that more stress-related morbidity categories tend to be over-represented in the higher density regimes than those morbidities categorized as non-stress related. In addition, it is found that those stress-related morbidities that exhibit such a pattern of over-representation maintain it, in general, regardless of the controls applied. Age is found to be negatively related to density and to the occurrence of stress-related morbidities, while being positively related to socioeconomic status. Socioeconomic status is found to be negatively related to both stress-related morbidity occurrence and to density. Social support is positively related to both density and to the occurrence of stress-related morbidities, but appears to have no relationship to either age or class. Hospital during 1974, and whose diagnosed morbidity was included in specific morbidity categories" All data were obtained through the facilities of the Health Services Research Center, Kaiser Foundation Hospital, Portland, Oregon.