PURPOSE: Despite improvements in surgical technique and expander design, problems remain when reconstructing mastectomy defects. These include extrusion, infection, wrinkling, and malpositioning of the expander. We report the use of Alloderm (LifeCell, Branchburg N.J.) to provide complete coverage and stabilization of the expander and avoidance of these potential complications. METHODS: Eight patients undergoing ten breast reconstructions with expanders had Alloderm sutured to the chest wall at the inframammary fold and to the inferior edge of the pectoralis. After expander placement, the lateral graft was sutured to serratus anterior, recreating the anterior axillary fold. Expansion and exchange of expanders for implants proceeded in normal fashion. RESULTS: Alloderm use allowed complete muscular and dermal graft coverage of the expander in each case. The inframammary and anterior axillary folds were precisely reconstructed. There were no cases of extrusion, infection, visible wrinkling, or lateral or inferior migration of expanders. At exchange, the Alloderm grafts were noted to be incorporated in the capsules. CONCLUSIONS: Alloderm use in breast reconstruction after mastectomy allows complete expander coverage, minimizing potential complications. The additional dermal layer prevents lateral and inferior migration of the expander, allows reestablishment of anatomic folds, and provides a suitably positioned envelope for subsequent implant placement.