BACKGROUND Past studies suggest multidisciplinary interventions that include physical therapy (PT) can improve function of nursing home residents. This trial specifically evaluates effects of PT for frail long-stay nursing home residents. METHODS Randomized, controlled trial. METHODS One academic nursing home and eight community nursing homes. METHODS A total of 194 elderly nursing home residents dependent in at least two activities of daily living residing in the nursing home for at least 3 months. METHODS Patients were randomized to individually tailored one-on-one PT sessions or friendly visits (FVs) three times a week for 4 months. Physical therapy included range-of-motion, strength, balance, transfer, and mobility exercises. METHODS Performance-based physical function assessed by the Physical Disability Index; self-perceived health status assessed with the Sickness Impact Profile; observer-reported activities of daily living; and falls. RESULTS Eighty-nine percent and 92% of PT and FV sessions, respectively, were attended; 5% and 9% of subjects dropped out in the PT group and FV group, respectively. Compared with the FV group, the PT group experienced no significant improvements in overall Physical Disability Index, Sickness Impact Profile, or activities of daily living scores. A 15.5% improvement in the mobility subscale of the Physical Disability Index was seen (95% confidence interval [CI], 6.4% to 24.7%); no benefits in range-of-motion, strength, or balance subscales were found. Compared with the FV group, the PT group used assistive devices for bed mobility tasks less often (P = .06) and were less likely to use assistive devices and wheelchairs for locomotion (P < .005). There were 79 falls in the PT group vs 60 falls in the FV group (P = .11). Charge for the 4-month PT program was $1220 per subject (95% CI, $412 to $1832). CONCLUSIONS This standardized physical therapy program provided modest mobility benefits for very frail long-stay nursing home residents with physical disability due to multiple comorbid conditions.