The victims were found bound and appeared to have been stabbed to death, according to Chihuahua state prosecutors.
Prosecution spokesman Arturo Sandoval said the bodies were found early yesterday and apparently were members of the same extended family.
He said exact ages were not yet available but three of the dead appeared to be children and five were adults.
Ciudad Juarez, across the border from El Paso, Texas, saw a huge spike in drug-related violence between 2008 and 2011, but killings have declined over the last year.
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Some of the bodies appeared to have been bound with cords. The graves were uncovered Saturday at a plant nursery in a rural area about a half hour from downtown Acapulco.
Drug gangs frequently use such burial sites to dispose of the bodies of executed rivals.
Once a glamorous beach resort, Acapulco in recent years has been the scene of turf battles between several small drug gangs.