The migrants were found sailing 32 nautical miles (36 miles; 59 kilometers) west of the islands of Paxos and were picked up by a nearby cargo ship, the coast guard said.
The cargo ship was heading to the western port of Patras, where the migrants would disembark. No information was immediately available on their nationalities or where they had set sail from.
Greece has been the main point of entry of hundreds of thousands of migrants heading into the European Union. Since an EU-Turkey deal limited new arrivals on Greece's eastern Aegean islands, many have been seeking alternative routes.