Two convicts managed to escape from a holding cell in Thessaloniki where there were awaiting transfer to Nigrita and Domokos prisons on Tuesday morning.
Police said the two Albanian men, aged 33 and 42, escaped through the cell window.
The bars on the window had been sawn off.
Officers warned that the 42-year-old should be considered dangerous.
He was convicted of two kidnappings and a murder.
He was arrested in January 2009 following a shootout with police.
The other prisoner was serving a sentence for drug-related offenses.
The police were searching for both men on Tuesday night.