Brief description of the article: This article considers heart rate variability as a measurable parameter of stress reaction and present recent studies that examined the impact of occupational stress on heart rate variability and thus autonomic nervous system.ABSTRACT Stress is a complex psychoneuroendocrinological and immune response of an individual to stressogenic factor. The most important contemporary stressogenic factors are mental, psycho-social and socio-economic stressors. This especially holds true for occupational stress. Many symptoms and signs of disease are associated with chronic occupational stress. Among those are cardiovascular diseases, metabolic and psychiatric disorders.This article describes different stressogenic factors that lead to occupational stress and two conceptual models of occupational stress (Karasek’s Demand/Control Model and Siegrist’s Effort-Reward Imbalance Model). Reaction to stress can be measured in various ways. This article summarizes the physiology of heart beat regulation and presents heart rate variability as a measurable parameter of stress reaction. Heart rate variability gives us an insight into autonomic modulation of the heart and functioning of the entire autonomic nervous system. This article presents the latest results of larger studies that examined the impact of occupational stress on heart rate variability and various mechanisms that lead to end-organ damage due to changes in autonomic nervous system as a result of work stress. Subjects exposed to chronic stress have significantly lower heart rate variability compared with subjects unaffected by stress. Researches have shown that reduced heart rate variability reliably predicts mortality among health adults, as well as morbidity and mortality in patients after acute myocardial infarction, in patients with chronic heart failure and mortality in patients with chronic kidney disease.