Crimea switched to Moscow time on Sunday by moving the clocks two hours forward.
According to the Crimean parliament, the schedules of Crimea's railway, water transport, air and telecommunications services all switched to Moscow time on March 30, Xinhua reported.
"The change is to proceed smoothly without financial or other losses," Crimea's first Deputy Prime Minister Rustam Temirgaliyev was quoted as saying.
Crimea's health ministry said that due to Crimea's geographical location, darkness falls earlier and the dawn too comes earlier than that in Kiev, so the time switch will have no negative impact on local people's life.
"If any impact is to be experienced, it will only be positive," the ministry said.
All of Ukrainian interior troops were also removed from Crimea on Sunday.
Russian President Vladimir Putin and Crimean leaders signed a treaty on March 18 for Crimea to become part of Russia.