OBJECTIVE: To assess the effects of low-frequency electric muscle stimulation associated with usual physiotherapy on functional outcome after total hip arthroplasty (THA) for hip osteoarthritis (OA) in elderly subjects. DESIGN: Randomized controlled trial; pre- and posttreatment measurements. SETTING: Hospital rehabilitation department. PARTICIPANTS: Subjects (N=29) referred to the rehabilitation department after THA for hip OA. INTERVENTIONS: The intervention group (n=16; 78+/-8 y) received simultaneous low-frequency electric muscle stimulation of bilateral quadriceps and calf muscles (highest tolerated intensity, 1h session, 5 d/wk, for 5 weeks) associated with conventional physical therapy including resistance training. The control group (n=13; 76+/-10 y) received conventional physical therapy alone (25 sessions). MAIN OUTCOME MEASURES: Maximal isometric strength of knee extensors, FIM instrument, before and after; a six-minute walk test and a 200 m fast walk test, after; length of stay (LOS). RESULTS: Low-frequency electric muscle stimulation was well tolerated. It resulted in a greater improvement in strength of knee extensors on the operated side (77% vs 23%; P<.01), leading to a better balance of muscle strength between the operated and nonoperated limb. The low-frequency electric muscle stimulation group also showed a greater improvement in FIM scores, though improvements in the walk tests were similar for the 2 groups, as was LOS. CONCLUSIONS: Low-frequency electric muscle stimulation is a safe, well-tolerated therapy after THA for hip OA. It improves knee extensor strength, which is one of the factors leading to greater functional independence after THA.