The objective of the study was to determine the incidence and predictors of post operative pain and flank bulging in patients undergoing nephrectomy for a renal tumor through a flank or thoracoabdominal incision. Only one previous retrospective study (1974) has directly addressed this issue in urologic patients. This reported a 3% incidence of flank bulging. This was at variance with our own experience. To determine the incidence of pain and post-operative flank bulge after flank or thoraco-abdominal incision, a cross sectional survey among in 70 patients, who had a nephrectomy for a renal tumor between 1996 and 2000, was assessed by telephone interview. Four surgeons contributed patients to the study. Thirty-four of seventy (49%) patients complained of a flank bulge persisting more than 1 yr after surgery. Durable flank pain was experienced by 24%. This was severe in 3% of patients. Median pain magnitude was 5/10. There was no difference in bulge incidence between surgeons (P = 0.49). Flank bulging occurred more frequently in left sided nephrectomy (P = 0.054) than right. Other parameters including gender, age, and tumor size had no correlation with the rate of either complication. In all patients who described a flank bulge, the deformity was durable; there were no cases of spontaneous resolution. Patients described a significant impact on QOL, particularly in those under 60 yrs. The overall rate of postoperative flank bulging is considerably higher than has been previously reported. This deformity affects quality of life. The observation that almost 50% of patients experience a flank bulge following a flank incision supports the shift towards laparoscopic nephrectomy, and should be incorporated into decision making regarding the optimal surgical approach. This may be particularly relevant in the choice between open partial nephrectomy and laparoscopic radical nephrectomy in a patient with a normal contralateral kidney.