['We noted that the impact of obesity on renal laparoscopy may vary with the specific surgical approach.', 'Patients who underwent standard and hand assisted laparoscopic radical nephrectomy at our institution were categorized by body mass index as nonobese--body mass index less than 30, obese--30 to 39.9 and morbidly obese--40 kg/m(2) or greater. We assessed the association of intraoperative and postoperative outcomes with body mass index for standard and hand assisted laparoscopic radical nephrectomy.', 'Of 350 patients who underwent standard (196) or hand assisted (154) laparoscopic radical nephrectomy 36% were obese and 12% were morbidly obese. Patients who underwent hand assisted laparoscopic radical nephrectomy had a greater body mass index, more frequent assignment of American Society of Anesthesiologists score 3 or 4 and larger masses than those who underwent standard laparoscopic radical nephrectomy. Despite this fact conversion to open surgery from hand assisted laparoscopic radical nephrectomy did not occur, while such conversion occurred in the standard laparoscopic radical nephrectomy group in 0.8% of nonobese, 3.0% of obese and 17% of morbidly obese patients (association with body mass index p = 0.003). Operative time, intraoperative and postoperative complications, and hospitalization duration did not vary with body mass index. On multivariate analysis only body mass index and not age, gender, American Society of Anesthesiologists score, prior abdominal surgery or tumor size was associated with an increasing likelihood of conversion to open surgery (p = 0.04), and only in the standard laparoscopic radical nephrectomy group.'] Are obesity and morbid obesity associated with a greater conversion rate to open surgery for standard but not hand assisted laparoscopic radical nephrectomy?