The water bomber crashed on Tuesday while fighting forest fires on the southern Greek island of Evia, fire department spokesman Yannis Artopios said.
"A Greek Canadair plane with at least two people on board crashed near Platanisto," Artopios said, referring to a village on the island.
The two pilots who died belonged to the Greek Air Force, according to information from the Ministry of Defence, quoted by state broadcaster ERT.
According to initial information from the authorities, the aircraft, which was taking part with at least three other aircraft and around 100 firefighters in the fight against the flames on the island near Athens, crashed into a ravine.
Greece has been plagued by fires and scorching temperatures for more than ten days.
The accident occurred on the heights of Karystos, where a fire started on Sunday.
ERT broadcast a video of the aircraft as it crashed and disappeared behind flames and a cloud of black smoke.