The bodies were lying on a road near the city of Iguala in the Pacific coast state of Guerrero.
The state prosecutors’ office said all the men had knife wounds on their faces and necks, suggesting their throats had been cut.
The bodies were found in an area that has been the scene of frequent turf battles between drug gangs. There are also vigilante-style forces active in the area that is sometimes associated with the gangs.
Guerrero is home to the Pacific coast resort of Acapulco, farther south.
Also Tuesday, authorities announced that skeletal remains found in November in the northern border state of Sonora were from 25 different people.
Volunteer searchers found 14 clandestine burial pits that contained bones, some burned, and decomposing bodies in a patch of scrubland. The remains were so jumbled that it took investigators more than a month to sort out the number of bodies.
The body dumping ground was discovered by volunteer search teams made up of relatives of disappeared people near a highway west of the state capital, Hermosillo. Relatives of the disappeared have to conduct their own searches in many parts of Mexico, because police are unable or unwilling to do so.
Sonora has been the scene of drug gang turf battles thought to involve factions of the Sinaloa Cartel, allies of the Jalisco cartel, and a gang allied with fugitive drug lord Rafael Caro Quintero.