Background: Lymphedema is one complication of breast cancer treatment and there is no consensus that identified one single therapy in the treatment of lymphedema; therfore an association of methods is recommended and one of these is exercising. The aim of this study was to evaluate the utilization of exercising with a facilitating device along with an arm compression sleeve to reduce the size of lymphedematous arms. Materials and Methods: Thirty women from a rehabilitation group with arm lymphedema resulting from the surgical, chemotherapeutic, and radiotherapeutic treatment of breast cancer were enrolled sequentially on arriving in the clinic. While sitting in an upright position and wearing an arm compression sleeve, patients were submitted to a one-hour session of active exercising consisting of four 12-minute stints with three-minute intervals to rest. The change in lymphedema was evaluated by water volumetry before and immediately after the session. The active exercising device is similar to the pedaling system of a bicycle. The paired t-test was employed for statistical analysis. An alpha error of 5% (p-value < 0.05) was considered acceptable. Results: A statistically significant reduction (p-value < 0.004) was noted in the size of the arm. Conclusion: Active exercising using a facilitating device and under supervision may reduce the size of lymphedematous arms.