The purpose of this study was to examine the influence of a fire-fighting training regime on the cardiac autonomic control of a middle-aged female diagnosed with smoldering multiple myeloma (SMM). Cardiac autonomic control was monitored by heart rate variability (HRV) analysis in the patient during the last six-week period of a one and half year training period. Compared with healthy, physically active age-matched females, the patient demonstrated similar HRV parameters. Furthermore, the patient experienced a positive evolution of the SMM during this training period. These findings indicate: 1) the beneficial effects of high intensity physical training on cardiac autonomic function in a SMM patient; 2) the potential value of HRV monitoring in cancer patients undertaking regular physical activity.