The military helicopter crashed into a field while on a training flight, the general staff said early on Tuesday morning.
The helicopter, a Bell Iroquois UH-1H Huey, crashed near the northern town of Karyotissa in the prefecture of Pella.
Authorities gave no immediate explanation for the accident, however Greek media claimed it was caused by mechanical failure in the ageing helicopter, apparently built in 1969.
The multi-purpose Hueys are among the oldest aircraft in Greece's arsenal.
The model first saw action with the US armed forces during the Vietnam War in the 1960s.
An opposition newspaper described the Greek army Huey as a "flying coffin".
A separate daily paper reported that 93 people have died in military aircraft crashes since 1990.
In September 2004, the Greek Orthodox Patriarch of Alexandria, Peter VII, died along with 16 other people when the Chinook military helicopter carrying them crashed near the northern peninsula of Halkidiki.