The purpose of this meta-analysis was to examine the effectiveness of aerobic exercise interventions on cardiopulmonary function and body composition in women with breast cancer. Of 24 relevant studies reviewed, 10 studies (N = 588) met the inclusion criteria. The findings indicated that aerobic exercise significantly improved cardiopulmonary function as assessed by absolute VO2 peak (standardized mean difference [SMD] .916, p < .001), relative VO2 peak (SMD .424, p < .05), and 12-minute walk test ( SMD .502, p < .001). Similarly, aerobic exercise significantly improved body composition as assessed by percentage body fat (SMD -.890, p < .001), but body weight and lean body mass did not change significantly. Aerobic exercise during or after cancer adjuvant therapy seems to be an effective means of improving cardiopulmonary function and decreasing percentage body fat in women with breast cancer. Further studies are needed to examine the long-term benefits of aerobic exercise.