INTERNATIONAL NEWS - Scores of migrants boarded ferries on the Greek island of Lesbos and arrived in Dikili, western Turkey.
The EU-Turkey deal has been attacked by rights groups and there are concerns over a lack of preparation.
Another ferry carrying migrants to Turkey is also due to leave the Greek island of Chios on Monday.
Greek authorities said the first people deported did not apply for asylum. There were also citizens from Bangladesh, Sri Lanka and Morocco.
The returns were carried out calmly, despite a small protest at the gate of Lesbos port, the BBC's Sarah Rainsford at the scene said.
Activists shouted 'No to deportations' and 'EU shame on you', our correspondent added.
Migrants in Greece have complained of a lack of information about the asylum procedure and some said they were unaware they could be returned.
Frontex has less than one-tenth of the staff needed to do the job, the Associated Press reported.
Under the deal, migrants arriving illegally in Greece are expected to be sent back to Turkey if they do not apply for asylum or if their claim is rejected.
For each Syrian migrant returned to Turkey, the EU is due to take in another Syrian who has made a legitimate request.
Turkey won financial and political concessions as part of the agreement.
