This systematic review and meta-analysis were undertaken to determine whether reduction mammaplasty improves measurable outcomes in women with breast hypertrophy. A systematic review of the literature in 5 languages from 1985 until March 1999 was performed, and data were compared for meta-analysis. Eligible studies were both experimental and observational and involved women with preoperative physical and/or psychosocial signs and symptoms who underwent reduction mammaplasty for breast hypertrophy. Outcomes assessed were postoperative physical signs and symptoms such as shoulder pain, shoulder (bra strap) grooving, and quality-of-life domains, such as physical and psychological functioning, and were expressed primarily as risk differences (RDs). Twenty-nine studies of 4173 patients met all eligibility criteria. Reduction mammaplasty was associated with a statistically significant improvement in physical signs and symptoms involving shoulder pain (RD, 0.71 [95% confidence interval (CI), 0.62-0.80]); shoulder grooving (RD, 0.69 [95% CI, 0.60-0.78]); upper/lower back pain (RD, 0.59 [95% CI, 0.48-0.70]); neck pain (RD, 0.50 [95% CI, 0.37-0.64]); intertrigo (RD, 0.44 [95% CI, 0.34-0.54]); breast pain (RD, 0.36 [95% CI, 0.17-0.55]); headache (RD, 0.28 [95% CI, 0.11-0.46]); and pain/numbness in the hands (RD, 0.11 [95% CI, 0.04-0.18]). The quality-of-life parameter of physical functioning was also statistically significant (RD, 0.58 [95% CI, 0.44-0.71]), while psychological functioning was not significant (RD, 0.46 [95% CI, 0.00-1.00]). The evidence suggests that women undergoing reduction mammaplasty for breast hypertrophy have significant postoperative improvement in preoperative signs and symptoms, quality of life, or both.