The charts of 44 women who underwent 47 immediate postmastectomy prosthetic breast reconstructions (IPMPBR) with subpectoral prostheses (long-term implant, long-term expandable implant or tissue expanders followed by long-term prosthetic placement) were retrospectively reviewed. Follow-up was from 3 to 49 months (median 18 months). Patient ages ranged from 31 to 77 years (median 42) but 82 per cent were under 60 years old. Indications for mastectomy were infiltrating cancer in 30 patients, intraductal cancer in 11, lobular carcinoma in situ in two and prophylaxis in one. There were 11 patients with pathologic Stage I, 15 with Stage II, three with Stage III and one with Stage IV breast cancer. Adjuvant chemotherapy (CTX) was given to 17 women, adjuvant hormonal treatment to nine, and radiation therapy (RT) to five. One patient had prosthesis extrusion and removal. Two patients had late periprosthetic infections (PPI) with consequent prosthesis removal. CTX did not have a significant association with PPI (two of 14 with CTX vs 0 of 29 without, P = 0.1). However, fill port migrations, prosthesis deflations, and greater than 1 complication were significantly associated with these infections (two of three vs 0 of 38, P = 0.004; two of two vs 0 of 45, P = 0.001; two of four vs 0 of 43, P = 0.006). Skin flap cellulitis and postoperative seroma were also associated with PPI (P less than 0.003 and less than 0.006, respectively). These factors were all also significantly associated with involuntary prosthesis loss (n = 3).(ABSTRACT TRUNCATED AT 250 WORDS)