Eighty six middle age patients with stage 1 hypertension were examined. Control group consisted of 38 patients with optimal or normal blood pressure. Heart rate variability indices which were calculated at rest with spectral analyses included high frequency power, low frequency power, ratio of low to high frequency power and total power. Plasma cortisol concentration was determined by immunoassay at 9, 10 and 11 o’clock in the morning. Obesity was defined according to body mass index measurement. Significant attenuation of HF, LF and TP (Р<0.001 in all cases) and enlargement of heart rate (Р<0.05) were revealed in hypertensive patients. This attenuation was still present in patients with arterial hypertension after body mass index standardization but became less significant (Р<0.01 for HF and TP; Р<0,05 for LF). Two types of diurnal cortisol curves were identified, one characterized by a high variability with high morning values, and another with low variability and low morning values. Blood pressure level, body mass index and heart rate variability were independent of cortisol secretion type.