Lymphoscintigraphy was used to measure lymphatic function at rest and during exercise in breast cancer survivors with lymphedema (BCRL, n=10), breast cancer survivors (BC, n=10), and controls (CONT, n=10). After injection of ^99mTc-antimony colloid to the hands, subjects rested or performed 12 repeated sets of arm cranking for 2.5 min at 0.6 W^.kg^-1 followed by 2.5 min of rest. 1 min spot views were taken with a γ-radiation camera immediately post-injection and every 10 min for 60 min to calculate clearance rate (CR). As well, an upper body scan was taken at 65 min post-injection to measure radiopharmaceutical uptake in the axilla (AX) and forearm (FORE). All groups displayed similar increases in CR with exercise (p=0.000). AX significantly increased with exercise in CONT only (CONT: (mean ±SD) 4.9% ±2.6 vs. 7.9% ±4.2, p=0.000; BCRL: 1.4% ±1.2 vs. 1.7% ±2.1, p=0.531; BC: 3.9% ±3.4 vs. 5.2% ±3.2, p=0.130) while FORE, indicating dermal backflow, significantly increased in BCRL only (BCRL: 2.4 ±0.87 vs. 4.4 ±2.0, p=0.004; BC: 1.1% ±0.25 vs. 1.1% ±0.31, p=0.784; CONT: 0.93% ±0.26 vs. 1.0% ±0.20, p=0.296). The results indicate that in women with BCRL, exercise causes radiopharmaceuticals to clear from the hand at the same rate as BC and CONT, but instead of reaching the axilla, a greater amount of activity gets trapped in the dermis of the forearm. BC, meanwhile, have similar lymphatic function as CONT; however, there is a highly variable response which may suggest that some BC subjects may be at risk for developing lymphedema.