Background: High insulin levels may be associated with an increased risk of colorectal cancer (CRC) development and recurrence. However, the effect of exercise on fasting insulin level in colorectal cancer survivors has not been fully studied. We conducted a randomized control trial to determine the effect of a 12-week home based exercise program on fasting insulin, body composition, and fitness in stage II-III CRC survivors. Methods: 123 stage II-III CRC survivors between 4 and 102 weeks after standard cancer therapy (surgery, chemotherapy, and/or radiation therapy) were randomly assigned to either the 12-week home-based exercise (n=62) or usual care (n=61) group. The goal of the home-based exercise was to increase the level of physical activity of the participants to 18-27 MET hours per week. The primary outcome measurement was fasting insulin and secondary outcome measurements were body composition and fitness level. Results: A total of 99 (80.5%) participants completed the trial. After 12 week of home-based exercise program, fasting insulin level was significantly reduced in exercise group while it did not change in control group (Ex, 6.09±3.96 vs. 4.93±3.41 µU/ml; Con, 6.74±3.40 vs. 6.73±3.01 µU/ml, between group p=0.045). Furthermore, percent body fat was significantly reduced (Ex, 27.53±8.59 vs. 26.83±8.41%; Con, 27.18±7.02 vs. 27.85±7.11 %, between group p=0.033), and 6-min walk test (Ex, 580.72±82.09 vs. 611.54±74.51 m; Con, 598.06±65.03 vs. 606.03±58.26 m, between group p=0.041), Chair Stand test (Ex, 19.71±6.53 vs. 23.08±5.06; Con, 23.87±6.20 vs. 23.83±4.31, between group p=0.004), and push up (Ex, 15.21±9.68 vs. 20.89±11.83; Con, 15.44±13.03 vs. 12.59±10.98, between group p <0.000) were significantly improved in exercise group. Conclusions: The 12-week home based exercise intervention decreased fasting insulin and percent body fat, and improved fitness in stage II-III CRC survivors. The current study was supported by the National Research Foundation of Korea (2013K2A1A2054437) and the National R&D Program for Cancer Control, Ministry of Health & Welfare, Republic of Korea (1120230).