A paratrooper, 44, died during an army exercise in Zhytomyr Region, the press service of the Airborne Troops Command of the Ukrainian Armed Forces has said.
"The reserve sergeant's heart stopped. According to a preliminary diagnosis, the man died from acute heart disease," it said.
Army doctors took required emergency measures but failed to save his life.
The command expressed condolences to the sergeant's family.
A day earlier, a contract soldier died after being ridden over by an infantry fighting vehicle in Chernihiv Region.