Government and rebel forces exchanged dozens of prisoners captured during fighting in Ukraine as part of a ceasefire agreement sealed earlier this month.
The transfer took place outside the main rebel stronghold of Donetsk early Friday under the watch of international observers.
President Petro Poroshenko said 36 Ukrainian servicemen were released after negotiations. He said another 21 soldiers were freed the day before.
Ukrainian forces handed over 31 rebels detained over the course of the five-month conflict.