Immediate breast reconstruction is offered to the majority of women requiring a mastectomy for cancer treatment. Improvements in implant technology have seen the evolution of shaped, fixed-volume implants and permanent expanders. The theoretical benefits of biodimensional anatomical expander implants include better reconstructed breast form, the potential for achieving this at a single procedure, and the avoidance of a contralateral procedure as a result of improved ipsilateral cosmesis. The aim of the present study was to assess outcome after immediate breast reconstruction using the McGhan 150 permanent expander implant. A total of 107 consecutive patients (129 breast reconstructions) were studied over a 30-month period; 49 patients (68 reconstructions) had submuscular implant placement alone, and 58 patients (61 reconstructions) had an implant in conjunction with a latissimus dorsi flap. The mean patient age was 47 years (range, 22 to 72 years) and the mean follow-up was 18 months (range, 6 to 40 months). Outcome was assessed in the following four ways: geometric measurements, evaluation of photographs by four independent observers, linear numerical analogue scale, and a quality-of-life questionnaire. Geometric measurements after surgery showed median differences that were highly consistent with good symmetry. Transverse breast width difference between breasts was 0.35 cm, vertical breast height difference was 0.8 cm, sternal notch-to-nipple distance difference was 0.6 cm, midclavicular line-to-nipple distance difference was 0.5 cm, nipple-to-inframammary crease distance difference was 0.5 cm, midline-to-nipple distance difference was 0 cm, and projection difference was 0 cm. Photographic assessment by four observers who evaluated shape, cleavage, symmetry, and overall outcome produced correlation values of 0.73 to 0.81. More than 75 percent of each of these parameters was scored as good or excellent. A numerical analogue scale (from 1 to 10) assessing overall result by the surgeon and patient revealed good (7 to 8) or excellent (9 to 10) scores in 83 and 82 percent of respondents, respectively. Quality-of-life data showed that 81 and 88 percent of women felt "a little" or "not at all" less feminine, respectively, and 88 percent were satisfied with the appearance of their breasts. A total of 88 percent of women would also choose the same reconstructive procedure if faced with the same cancer diagnosis. Complication rates were low; infections occurred in 6.2 percent of reconstructions, hematoma occurred in 1.6 percent, and implant loss occurred in 3.9 percent. Only 24 of 107 patients (22 percent) elected to have a synchronous contralateral breast adjustment, and four of 107 (4 percent) chose to have a subsequent procedure for symmetry. Biodimensional expander implants used in immediate breast reconstruction are associated with high levels of patient and surgeon satisfaction. Optimum breast form can be achieved during a single operation with a low incidence of complications.