Three migrants were taken to hospital on the eastern Aegean island of Chios late Saturday after clashes broke out between Afghans and Iraqis of Kurdish origin at Souda camp.
Authorities said the victims had been injured by a sharp object.
Police were sent in to stop the violence. One person was detained.
Meanwhile, also on Saturday, an unidentified number of migrants on the island of Lesvos staged a rally to protest delays in processing their asylum applications.
Last week migrants attacked the premises of the European Asylum Support Office (EASO) inside the Moria hot spot on Lesvos during a protest that was contained by riot police.