Three headless bodies showing signs of torture were found just outside Acapulco and the bodies of five other men with multiple gunshot wounds were discovered in a car north of the Pacific resort, Mexican police said.
Police in the southwestern state of Guerrero, where Acapulco is located, said the three beheaded men appeared to be in their 20s and 30s, but their identities and a motive had not been determined.
They were found on a peninsula a few miles south of Acapulco.
About 50 miles north, near the small town of Tecpan de Galeana, police discovered five bodies in a car left on a dirt road about 100 yards off a main highway.
A police report said all five men were repeatedly shot. Two bodies were in the front of the vehicle and three in the trunk, the report said.
The US State Department warned this week that parts of Guerrero state could be dangerous for travellers due to drug violence.
At the same time, the travel warning noted that Mexican officials make a concerted effort to protect foreign tourists and that "resort areas ... in Mexico do not see the levels of drug-related violence and crime reported in the border region and in areas along major drug trafficking routes".
More than 22,700 people have been killed in drug-related violence since President Felipe Calderon launched an offensive against cartels shortly after taking office in December 2006.