We reviewed our experience with 2-stage revision of uncemented Kotz Modular Femoral and Tibial Replacement System prostheses from 1989 to 2004. A total of 180 lower extremity tumor prostheses were inserted, 15 of which underwent removal of the prosthesis for infection. Eleven patients underwent subsequent second-stage revision, and 4 underwent amputation. Of the 11 patients who underwent revision, 8 continue to be free of infection an average of 33 months postoperatively. Of these 8 patients, 6 were revised without removal of the diaphyseal anchorage piece, which were all well ingrown. Most successful revisions were in the group that developed infection within 6 months of their original procedure. Two-stage revision of uncemented tumor endoprostheses with retention of a well-ingrown stem can be associated with successful eradication of infection.