In a study of 989 middle-aged men followed up for 9 years social influences, measured as persons per household unit, home activities, outside-home activities, and social activities at the baseline examination, were found to be significantly associated with mortality. The association between these variables (except for home activities) and mortality was significant even when age, risk factors for coronary heart disease, and health status measured at the baseline examination were taken into consideration. Social activities may have a modifying effect on life stresses and risk factors associated with mortality.