This research sought to identify the determinants of nonuse and high use of physician services and assess whether or not patterns of nonuse and high use changed over time. The population of interest was a group of elderly unmarried women who participated in the Longitudinal Retirement History Survey from 1969 to 1979. Andersen and Newman's (2) health care services utilization model served as the conceptual framework for this research. Of specific interest was the relationship between age strata and health care behavior. Age proved to be a stratifying variable within the health care delivery system. Over the ten year survey period, the health care behavior of preretirement and postretirement nonusers and high users differed significantly. A decline in nonuse was also associated with the transition years. This finding could be attributed to the "near poor" becoming eligible for Medicare. In any event, these data show that utilization of physician services is likely to increase among some unmarried women in their middle 60's.