We evaluated patients who underwent surgery for implant malfunction to determine whether retaining the reservoir was associated with an increased risk of erosion or infection. We also reviewed the literature to study possible risk factors for reservoir erosion. We reviewed the records of 85 patients who underwent 98 procedures for replacement of a malfunctioning 3-piece penile implant. Of these patients 13 underwent 2 replacement procedures. At the time of primary surgery the reservoir was placed in either the retropubic space or extraperitoneally in the lower lateral abdomen if the patient had undergone prior pelvic surgery. During surgery for replacement of the malfunctioning implant the cylinders and pump were removed, and the reservoir of the original 3-piece device was retained. During followup patients were assessed for implant function and the development of any complication such as infection and/or reservoir erosion into the bladder or bowel. Infection developed in 1 patient and implant malfunction occurred in 13 but no patient had erosion of the retained reservoir. All 85 patients had a functioning implant at a mean followup of 50 months (range 12 to 148). Review of the literature suggests that prior pelvic surgery and infection are major risk factors for reservoir erosion. Retaining the reservoir during replacement of malfunctioning 3-piece implants is not associated with a significant risk of erosion and routine removal is not necessary. Prior pelvic surgery and infection appear to be risk factors for reservoir erosion.