Media reports from the South American nation said the killings occurred that the Cabimas and San Felipe prisons following prison fights. At least 16 others were reportedly injured.
Media reports said that one group of inmates at the San Felipe prison were vying for control of the prison and killed a leader of a rival group.
At Cabimas, authorities said one prisoner was killed and 16 others were being treated for burns after violence broke out there.
The latest upheaval in Venezuelan prisons comes after a 27-day uprising in El Rodeo jail, on the outskirts of Caracas. That ended without bloodshed following negotiations between inmates and authorities.