Purpose: To explore cardiac autonomic changes assessed by linear and nonlinear indexes of heart rate variability (HRV) and body composition modifications in breast cancer survivors and cancer-free control women. Methods: Women who were breast cancer survivors (BCS, n=27) and cancer-free control participants with similar characteristics (Control, n=31) were enrolled in the Regional General Hospital No. 251 of the Mexican Institute of Social Security (Metepec, Mexico). We processed five minutes of R-R interval time series, and we calculated relevant linear and nonlinear parameters of HRV such as mean RR interval (RRave), the Root Mean Square of the Successive Differences (RMSSD), the Poincaré plot measures SD1, SD2, SD1/SD2, and the sample entropy (SampEn). Additionally, we indirectly assessed body composition measures such as body weight, fat mass, visceral fat rating (VFR), normalized VRF (nVFR), muscle mass, metabolic age, and total body water.Results: We found that diverse HRV indexes and only one body composition measure showed statistical differences (p<0.05) between the BCS and Control groups: RRave: 729 (648–802) vs. 795 (713–852) ms; RMSSD: 16.5 (8.9–27.0) vs. 19.7 (14.2–28.5) ms; SD1: 11.6 (6.3–19.0) vs. 13.9 (10.0–20.1) ms; SD1/SD2: 2.5 (2.1–3.3) vs. 2.2 (1.9–2.7), SampEn: 1.5 (1.3–1.8) vs. 1.7 (1.5–1.8), and nVFR 0.12 (0.11–0.13) vs.0.10 (0.08–0.12) points/kg, respectively. The nVFR was significantly correlated to several indexes of HRV.Conclusions: BCS exhibit a lower parasympathetic cardiac activity and changes in HRV patterns than controls, likely because of the concomitant increase of visceral fat.