Recent studies have established the cost effectiveness and safety of total joint arthroplasties. As the population ages, it is important to determine whether these procedures are equally beneficial in the elderly. The short term safety and efficacy of total hip and knee arthroplasties in subjects 80years of age and older was evaluated. Between 1988 and 1993, preoperative and postoperative physical and functional information was collected on 99 consecutive elective hip and knee arthroplasties in subjects 80years of age or older. These data were compared with those derived from a younger otherwise matched control group. Data collected included subject demographics and characteristics, information concerning the acute and postacute hospital stay, comorbid conditions, postoperative complications, discharge disposition, Hospital for Special Surgery knee and Harris hip scores, pain scores, and functional capacity. The average age of the subjects was 83 years; osteoarthritis was the most common diagnosis; and the average followup was 25 months. Complication rates and length of stay in acute care facilities were not significantly different than for the control group. Mean preoperative Hospital for Special Surgery knee and Harris hip scores were 58 and 60, respectively, with postoperative scores of 77 and 88, respectively. Pain dramatically improved with 98% of total knee arthroplasty and 100% of total hiparthroplasty subjects reporting mild or no pain at followup. Preoperatively, none of the knee or hip subjects could walk unlimited distances. Postoperatively 51% of the total knee arthroplasty and 54% of the total hiparthroplasty subjects could walk more than five blocks; 71% of the total knee arthroplasty and 86% of the total hiparthroplasty subjects walked with a cane or no assistive device. The most dramatic postoperative functional gains were seen in the most disabled subjects. Total charges of care for patients 80years of age and older was slightly greater than for a younger group. It was established that total joint arthroplasty can be performed safely in patients 80years of age and older, promising excellent pain relief and improved functional outcome.