The migrants, of apparent Afghan origin, were mostly in good condition but seven received first aid in hospital, police reported.
Forty-one migrants were found alive in a refrigerated truck in northern Greece on Monday, said police, who arrested the driver.
The migrants, of apparent Afghan origin, were mostly in good condition but seven received first aid in hospital, said the police.
"The truck contained men and boys. Identifying their nationality will require a couple of days," a police source told AFP.
The truck was stopped by police on the Egnatia motorway between the towns of Xanthi and Komotini.
The driver, a man from Georgia, was arrested.
Local media reported that police were also seeking a second man from Turkey in connection with the incident.
The discovery came after 39 people, all believed to be Vietnamese nationals, were found dead in a refrigerated truck in Britain last month, highlighting the risks of illegal migrant routes to Europe, even for those avoiding perilous travel by sea.
Greece is experiencing its highest asylum-seeker arrival figures since 2016, when a controversial deal between the EU and Turkey stemmed previous flows of nearly a million people.
Scores arrive daily, overwhelming camps on Greek islands facing Turkey where over 34,000 people are staying, most of them in deplorable living conditions.
A two-year-old girl from Iraq died Monday when she was hit by a car on the island of Chios, state agency ANA said.