Crotalus molossus oaxacus, or the Oaxacan black-tailed rattlesnake, is a subspecies of black-tailed rattlesnake which is native to its namesake, Oaxaca, Mexico. As with all rattlesnakes, it is venomous. While it is currently recognised as a subspecies, it has been suggested to be further researched and reviewed as a species by Muñoz-Mora et al. due to its being the basal and most divergent clade of the species, splitting around 7.5 million years ago in the Miocene.
Crotalus molossus oaxacus is known to eat a variety of rodents, such as the Northern Pygmy Mouse and the Mexican spiny pocket mouse.
Crotalus molossus oaxacus is known to be ovoviviparous.