The objective of this study was to determine the effects of exercise training on changes in C-reactive protein (CRP) and other cardiovascular risk factors in postmenopausal breast cancer survivors. Fifty-three postmenopausal breast cancer survivors were randomly assigned to an exercise (n = 25) or control group (n = 28). The exercise group trained on cycle ergometers 3 times per week for 15 weeks. The control group did not train. The primary end point was change in CRP between baseline and week 15. Secondary end points were changes in RHR, HRR, SBP, DBP, TC, LDL-C, HDL-C, TG, and TC:HDL-C ratio. Fifty-two participants completed the trial. Baseline values did not differ between groups except that TG (p = .007) and TC:HDL-C ratio (p = .023) were higher in the exercise group. Intention-to-treat analysis showed that CRP decreased by 1.39 mg/L in the exercise group whereas it increased by 0.10 mg/L in the control group (mean between group change, -1.49 mg/L; 95% CI, -3.09 to 0.10 mg/L; p = .066). Intention-to-treat analysis also showed a clinically and statistically significant difference between groups for change in HRR (mean change, +10.6 beats/min; 95% CI, +3.4 to +17.7 beats/min; p = .004) and clinically but not statistically significant differences between groups for change in RHR (mean change, -5.5 beats/min; 95% CI, -11.5 to +0.5 beats/min; p = .073), SBP (mean change, -5.5 mmHg; 95% CI, -14.5 to +3.4 mmHg; p = .218), DBP (mean change,-3.6 mmHg; 95% CI, -9.3 to +2.1 mmHg; p = .214), and HDL-C (mean change, +0.05 mmol/L; 95% CI, -0.03 to 0.14 mmol/L; p = .214). These data suggest that exercise training may have beneficial effects on CRP and other cardiovascular risk factors in postmenopausal breast cancer survivors. Larger randomized controlled trials are warranted.