OBJECTIVE: Inflammation plays a role both in the mechanisms leading to hypertension alone and in the mechanisms leading to atherosclerosis with hypertension. Previous studies have shown the relationship between the autonomic functions and inflammatory system activation. The aim of the study was to evaluate the relationship between inflammation and cardiac autonomic functions in hypertensive patients. METHODS: One hundred twenty one hypertensive patients (mean age 59 +/- 11 years, 60 male) and 34 healthy volunteers (mean age 58 +/- 11 years, 18 male) were included in the present cross-sectional observational study. The 24-hour ambulatory electrocardiogram recordings were taken using Pathfinder Software. The heart rate variability (HRV) analysis was performed using time domain parameters using the same software. Heart rate turbulence (HRT) parameters, turbulence onset and turbulence slope were calculated with HRT software. Statistical analysis was performed using unpaired t-test or Mann-Whitney U test, one-way ANOVA or Kruskal-Wallis analysis of variance, Chi-square test, and Spearman rank order correlation analysis. The association of hypertension with high sensitivity C-reactive protein (hs-CRP), HRV and HRT was analyzed after adjustment for confounding variables as age and creatinine levels. RESULTS: The mean hs-CRP was higher, HRV was slightly reduced while HRT was markedly blunted in hypertensive patients in comparison with control group [SDNN; 132 +/- 28 vs. 112 +/- 34 msec, RMSSD; 27 (23-35) vs. 22 (16-28) msec, TO; -2.80 +/- 2.15 vs. -0.96 +/- 2.36%, TS; 7.56 (5.24-10.60) vs. 4.65 (2.44-7.26) msec/RR, p<0.01 for all]. All of the HRV and HRT parameters were more deteriorated in the highest tertile hs-CRP group [SDNN; 93 +/- 34 msec, RMSSD; 17 (13-22) msec, TO; 0.03 +/- 2.22%, TS; 2.43 (1.84-3.89) msec/RR, p<0.05 for all]. There were correlations between hs-CRP and HRV and HRT parameters (SDNN; r=-0.690, RMSSD; r=-0.277, TS; r:-0.417, TO; r=0.267, p<0.05 for all). CONCLUSION: There is an inflammatory process in hypertensive patients and inflammation is related with unbalanced cardiac autonomic functions.