Age is one of the main known risk factors for cardiovascular diseases. The ageing of the body and arterial hypertension are associated with progressive dysfunction of the autonomic nervous system, which may be one of the mechanisms underlying an increased cardiovascular risk. The aim of the paper was to assess heart rate variability parameters in the age subgroups of patients with arterial hypertension. The heart rate variability parameters were compared in a total of 139 patients with untreated arterial hypertension (mean age 45.2 ± 10.5 years, men – 69% of the study group) in the following subgroups distinguished by age: ≥45 years (n = 72) and <45 years (n = 67). A temporal analysis of the heart rate variability parameters in 24-hour Holter ECG (SDNN, rMSSD, pNN50) was conducted for 24 hours, and for the day and night periods. In addition, a spectral analysis (LF, HF, TP, LF/HF ratio) was performed. The recorded values of SDNN, rMSSD, pNN50, TP as well as night-time HF were lower in the group of patients aged ≥45 years compared to the younger group. The results confirm that in patients with arterial hypertension older age is associated with a shift of the autonomic balance towards sympathetic activity, which may translate into an additional increase in cardiovascular risk.