Introduction. To evaluate the relationship between lymphedema, posture, respiratory functions, exercise capacity, and the quality of life after breast cancer treatment. Methods. This cross-sectional study consisted of 38 women who had unilateral breast cancer treatment. Pulmonary function with a spirometer, functional exercise capacity via 6-minute walking test, postural alignment changes, and quality of life were evaluated. Circumferential measurements were used to determine the severity of lymphedema. Results. The median age of female participants was 53 years (range, 40-64). The mean body mass index was 26.66 ± 2.96 kg/m 2 , of which 76% had lymphedema. The expected changes in posture were moderate. The mean of the 6-minute walking distance decreased, which corresponded to 58.55% of normative values. MIP and MEP values were significantly lower than expected values. An intermediate negative correlation was observed between postural changes and body mass index (r = -0.348; p = 0.05). Moreover, there was a positive correlation between forced expiration volume and forced vital capacity values and walking distance (p < 0.05). Conclusion. After breast cancer treatment, 76% of female patients had lymphedema, the functional exercise capacity, MIP and MEP were below the expected values in all of them, and as functional capacity decreases, respiratory parameters affected negatively.