The Mexican navy has rescued two Colombian and two Ecuadorean fishermen off the coast of the southern state of Chiapas.
The fishermen said they had been adrift at sea for 30 days after their boat ran out of petrol.
They said the currents carried them north from the waters off Ecuador to Mexico.
Doctors said the four were dehydrated. It is not clear what they lived off while adrift.
Navy personnel carrying out a routine night flight spotted their boat 260km (162 miles) off the coast of Chiapas.
The four said they had sailed from the port of Esmeraldas in Ecuador on 24 September and had run out of fuel on 1 October.
Currents have been known to carry castaways for thousands of kilometres.
In 2006, three Mexican fishermen were rescued off the Marshall Islands in the Pacific after what they said was about nine months drifting across the Pacific Ocean.
And in February 2014 a Salvadorian castaway was rescued also off the Marshall Islands more than a year after he said he sailed in a fibreglass boat from Mexico.