Mojave rattlesnake (Crotalus scutulatus scutulatus) identification has important diagnostic and therapeutic implications. Envenomation by certain populations of Mojave rattlesnakes may cause a different clinical presentation than that caused by other rattlesnakes. Specifically, Mojave rattlesnake envenomation may cause fewer local effects and more neurologic effects (including respiratory difficulty) than are typically seen after bites from other types of rattlesnake. Thus, it is useful for clinicians to distinguish the Mojave rattlesnake from other rattlesnakes in order to prevent underestimation of severe envenomation because of the lack of local tissue injury. Patients suspected to have been bitten by Mojave rattlesnakes may need more aggressive treatment with antivenin as well as more intensive supportive care. In addition, patients suspected to have been bitten by Mojave rattlesnakes should be closely monitored for an extended observation period, as venom effects may be delayed or prolonged. Mojave rattlesnakes may be particularly difficult to distinguish from Western Diamondback rattlesnakes (Crotalus atrox) because of their similarity in appearance and overlapping ranges. The purpose of this report is to provide clinicians with key characteristics which may assist in distinguishing Mojave rattlesnakes from Western Diamondback and other rattlesnakes.