Aim: to reveal the features of cardiovascular system functional reserves in naval cadets under the conditions of a long voyage.Materials and methods. 70 cadets undergoing training and sailing practice for 165 days on Sedov training and sailing ship were studied. Cardiovascular system reserves were determined once a month indices before taking over the watch. The results were elaborated using the SPSS program, v 17.0 (IBM).Results and their discussion. On the first, second, and third months of the voyage, the naval cadets retained the functional reserves of the cardiovascular system, which is indicated by the typical normotonic reaction in its activity in response to physical activity.On the fourth and fifth, the cadets showed signs of a decrease in the reserves of the cardiovascular system, which is manifested by a slower recovery after standard physical activity, a decrease in the inotropic reserve index and an increase in the chronotropic reserve index.