According to survivors, there were no other people on board the boat.
At least one migrant has died after a small boat sank in the Aegean Sea, the Greek coastguard said on Thursday.
Ten other people were rescued by two patrol boats near the island of Kos late on Wednesday, the authority added.
After receiving a distress call, Greek authorities said they found all 11 men in the water.
One of the migrants was found unconscious and was later pronounced dead on arrival at the port of Kos.
"According to the rescuers, there were no other people on board the boat," the coastguard said in a statement.
The incident comes just weeks after at least 23 people died when two migrant boats sank near the islands of Evia and Samos. Several others remain missing.
Greece is one of the main destinations for migrants from Africa and the Middle East seeking to reach Europe.
The Greek coastguard says it rescued around 1,500 people in the first eight months of 2022, compared with fewer than 600 last year.