Obesity is considered an independent risk factor for adverse outcome after arthroplasty surgery. Data on 191 consecutive total hip arthroplasties were prospectively collected. Body mass index (BMI) was calculated for each patient and grouped into nonobese (BMI <30 kg/m2), obese (BMI 30-34.9 kg/m2), and morbidly obese (BMI ≥35 kg/m2). Primary outcomes included functional improvement (Oxford hip score, 6-minute walk test and Short Form-12 Health Survey general health questionnaire) and postoperative complications. Subgroup analysis of surgeons’ overall perception of operative technical difficulty was also performed. This study shows that total hip arthroplasties in obese patients were perceived, by the surgeon, to be significantly more difficult. However, this did not translate to an increased risk of complications, operation time, or blood loss, nor suboptimal implant placement. In addition, our results suggest that obese patients gain similar benefit from hip arthroplasty as do nonobese patients, but morbidly obese patients have significantly worse 6-minute walk test scores at 6 weeks.