PURPOSE: To examine the effect of one bout of exercise on the metabolic biomarkers responses of breast cancer survivors (BCS) and healthy sedentary women controls (SW). METHODS: 9 women who completed major treatments for Stage I-III invasive breast cancer within 3-6 months and 9 SW without a history of cancer diagnosis completed a 30-minute bout of intermittent cycle ergometry exercise at 60% of VO2peak. Blood was taken pre-exercise, immediately post-exercise, and 2 hr post-exercise and analyzed for blood lactate, glucose and free fatty acid (FFA) concentrations. RESULTS: Peak exercise lactate responses of BCS were significantly lower than SW (p<0.01). No differences existed in glucose responses for BCS and SW. BCS FFA response at 2 h post exercise was greater than SW (p<.05). CONCLUSIONS: Findings support that BCS do not have the same metabolic responses to exercise as non-cancer patients. The reason for the differing metabolic responses is unclear.