The immigrants were taken to a hospital at the port of Lavrion, 55 kilometers (35 miles) southeast of Athens, to be examined by doctors, the Merchant Marine Ministry said.
Details of their nationalities were not immediately available.
Port officials said there were at least 16 women and children among the rescued. They said the immigrants traveled in a fishing boat from the coast of Turkey.
No other details were immediately available.
Greece is a busy transit point for human trafficking, with illegal immigrants seeking access to European Union countries.
The choice of the city of Helsinki is not incidental as the capital of Finland had hosted US-Soviet negotiations on the limitation of nuclear stockpiles in 1969