People march in the Ukrainian capital, Kyiv, on Defenders Day.
Participants hold photos of relatives who have died in the conflict with separatist forces in eastern Ukraine.
The holiday honors veterans and Ukrainians currently serving in the military, as well as those who lost their lives in combat.
The new holiday, established in 2015, took the place of a commemoration dating back to the Soviet era, Defenders of the Fatherland Day, formerly held in February.
The march in Kyiv drew members of nationalist and far-right organizations, including militiamen who have fought in the conflict in Donbas.
October 14 was considered a controversial choice of date for the newly created holiday.
Along with marking an Orthodox Christian holiday, October 14 also marks the creation of the Ukrainian Insurgent Army (UPA), which fought against both Soviet and Nazi forces during World War II. The group was also accused of massacring Poles and Jews.
Servicemen and hundreds of others marched in the western city of Lviv.
Members of the military take part in the Defenders Day event in Lviv.
Photos of victims of the conflict in eastern Ukraine were on display in the city of Zaporizhzhya.
A woman holds a flower during the march in Zaporizhzhya.
Servicemen attend a Defenders Day event in Kharkiv.
Some marchers in Dnipro carried the black and red flag of the UPA.
Several hundred people took part in the march in Dnipro.