Back ground: The technique of utilizing acellular dermal matrices in immediate breast reconstruction with expanders or implants is becoming popular, as they add additional coverage at the lower pole. Multiple products have been introduced and much has been stated about the sterility of products as this still poses questions to surgeons. The purpose of this series is to evaluate the safety and morbidity of AlloDerm (LifeCell Corp., Branchburg, N.J.) in post mastectomy reconstruction in 2 center, 2 surgeon independent practices. Methods: Results of 264 consecutive patients with breast expander reconstructions (461 breasts) performed by two surgeons at two centers between 2007 and 2009 were retrospectively reviewed. Patient demographics, expander type, adjuvant treatment, and incidence and types of complications were recorded. All patients underwent first stage expander reconstruction with complete expander coverage with pectoralis major and acellular dermal matrix (AlloDerm, Lifecell). This was then followed by 2nd stage reconstruction which included placement of permanent silicone prosthesis and additional acellular dermal matrix. Results: A total of 264 patients underwent 429 immediate and 32 delayed reconstructions. The average age was 49 years (range: 28-76), with an average body mass index of 28.1 (range: 19-43). Of the 429 immediate reconstructions three breasts had pre-operative radiation therapy and 7 underwent post operative radiation therapy. Neoadjuvant therapy was administered to 9 of immediate reconstructions. Of the 32 delayed reconstructions 12 breasts had pre-operative radiation therapy. Average follow up included 9.2 months (3-27months). Eleven (2.38%) failed expander implant reconstruction: (4/11 tobacco use; 4/11 pre-op chemotherapy which included Cisplatin/Bevacizumab; 3/11 pre-op radiation therapy; 4/11 BMI>35). All patients with the implant loss, had expander exposure and infection that were not salvageable. The remainder underwent expansions without difficulty and secondary implant insertion demonstrated incorporation of the AlloDerm. At follow up the following was noted: 409 breasts with Baker 1, 39 breasts with Baker 2, and 2 breasts with Baker 3. CONCLUSIONS: This study demonstrates that prosthetic breast surgery using AlloDerm is safe and well-tolerated with failure and infection rates similar to reported percentages with different types of expander coverage. As always appropriate patient selection for expander based breast reconstruction should be of outmost importance.