The role of sex steroids in coronary artery disease (CAD) has been studied for years. In patients after myocardial infarction autonomic nervous system dysfunction has been described. Heart rate variability (HRV) analysis is one of the method of autonomic nervous system evaluation. The aim of the study was to evaluate correlations between sex steroids and HRV in 88 men (aged 36-73, av. 53 yrs), with the history of MI, with angiographically documented CAD. In all the patients 24-hour Holter monitoring was performed to assess HRV time domain parameters: SDNN, SDNNI, SDANN, rMSSD, pNN50. Levels of testosterone and estradiol were measured in two subsequent blood samples, taken with 30 min interval. Free testosterone index as well as estradiol/testosterone ratio were assessed. For statistics r-Spearman test was used. Positive correlations were found between testosterone and SDNN (r = 0.38, p = 0.03), testosterone and rMSSD (r = 0.51, p = 0.002) and between testosterone and pNN50 (r = 0.45, p = 0.007). Since rMSSD and pNN50 are parameters describing parasympathetic activity, our results suggest that in CAD men with the history of myocardial infarction, testosterone may influences the function of autonomic nervous system promoting parasympathetic dominance. It can be favorable for the circulatory system function.