OBJECTIVE: To determine whether psychosocial factors, chronic diseases, and common geriatric problems are associated with poor physical function 3 years after primary total hip replacement (THR). METHODS: We studied a sample of Medicare recipients in Ohio, Pennsylvania, and Colorado (n = 922) who underwent primary THR in 1995 (mean +/- SD age 73.1 +/- 5.6 years, 32% men). Participants completed a questionnaire regarding lifestyle factors, medical history, and quality of life approximately 3 years after the surgery. Physical function was measured using the function subscale of the Western Ontario and McMaster Universities Osteoarthritis Index. We assessed the relationship between functional outcome 3 years postsurgery and 4 predictor domains: pain or complications in the operated hip, other musculoskeletal comorbidity, medical factors (obesity, chronic medical comorbidity, rheumatoid arthritis, and such common geriatric problems as falls, poor balance, or incontinence), and psychosocial factors (mental health, regular alcohol consumption, smoking, provider role, living alone, and education). RESULTS: Ten percent of subjects had poor functional status. In a logistic regression model controlling for sex and age, the following factors were associated with an increased risk for poor functional status (in order of importance): pain in the back or lower extremity, severe pain in the operated hip, poor mental health, more than 1 common geriatric problem, obesity, and less than college education. CONCLUSION: Pain in the operated hip was strongly associated with poor functional status 3 years after THR. However, other factors associated with poor functional status were not related to the hip. Our results suggest that a comprehensive assessment of functional status in elderly THR patients should include assessment of common geriatric problems, mental health status, and weight.