Jailed Kurdish militant leader Abdullah Ocalan used the Kurdish new year celebrations to order his fighters to cease fire and withdraw from Turkish soil.
Hundreds of thousands of Kurds massed for the festivities listened to Ocalan's message being read out.
The move marks a major step toward ending a conflict that has killed 40,000 people.
The ceasefire could cement peace talks with Turkey, with the fighters withdrawing to their bases in the mountains of northern Iraq.
Truces have been declared and secret talks held with Ocalan's Kurdistan Workers Party in the past, but expectations are high this time.
The PKK, regarded by the United States and the European Union as well as Turkey as a terrorist organisation, launched its campaign in 1984, demanding an independent Kurdish state in the southeast of Turkey.
But in recent years it has moderated its demands to political autonomy and broader cultural rights.
