The purpose of this study was to examine the health service utilization patterns of elderly male and female enrollees of a large urban staff model Health Maintenance Organization (HMO). This HMO offered a wide spectrum of managed care services for its beneficiaries. A cross-sectional design was employed. The 759 randomly sampled elderly enrollees ranged in age from 66 to 99, with an average of 77.15 years. Approximately 60% were male and 40% were female; thus, the sample was not representative of the national older adult population. Three utilization patterns indicated that there were (a) nonsignificant relationships between age or gender and urgent care visits, prescribed pharmaceuticals, and out-of-pocket costs for pharmaceuticals; (b) linear relationships between age and gender and visits to HMO primary care providers (−), home-health care visits (+), emergency care visits (+), hospitalizations (+), and MD visits during hospitalizations (+); and (c) age was curvilinearly related to use of both HMO specialists and non-HMO specialists. These findings suggest that use of acute care services, including hospitalizations, inpatient physician visits, and emergency services increase with age but the use of primary care providers decreases with age. Gender was not a significant modifier of the relationship between age and utilization. © 1996 John Wiley & Sons, Inc.