Background: Heart rate variability has been intensively explored during the last decade as a marker of autonomic modulation of the heart and thus used for prediction of the risk of cardiac mortality. Objectives: To evaluate the methodology of heart rate variability measurement and make primary obsenvations of the HRV data of 20 - 24 year-old students. Method: Participants were 76 volunteered medical students, 38 men and 38 women.