Under a pact criticized by refugee agencies and human rights campaigners, Ankara will take back all migrants and refugees who cross the Aegean to enter Greece illegally, including Syrians.
In return, the European Union will take in thousands of Syrian refugees directly from Turkey and reward it with money, visa-free travel and progress in its EU membership negotiations.
Two Turkish passenger boats carrying 136 mostly Pakistani migrants arrived from the island of Lesbos in the Turkish town of Dikili, accompanied by two Turkish coast guard vessels with a police helicopter overhead.
A third ship carrying 66 people, mainly Afghans, arrived there later from the island of Chios.
The EU-Turkey deal aims to discourage migrants from perilous crossings, often in small boats and dinghies, and to break the business model of human smugglers who have fueled Europe's biggest influx since World War Two.
Turkish President Tayyip Erdogan excoriated European governments' response to the crisis even as his government cooperated with the EU scheme.
EU authorities said none of those deported on April 4 had requested asylum in Greece and all had left voluntarily. They included two Syrians who had asked to return to Turkey.
European Commission spokesman Margaritas Schinas said the first returns were legal, even though Turkey has not yet made changes to its regulations that the EU said were necessary at the time of the deal.
The EU said at the time of the deal that Ankara would need to change asylum laws to give international protection to Syrians who enter from countries other than Syria, and to non-Syrian asylum seekers returned from Greece.