The Great Basin Gopher Snake is large and robust with adults ranging from 76 -180 cm in British Columbia (St. John 2002). Body colour is tan with a row of dark brown or black blotches along the middle of the back and tail. The ventral surface is creamy yellow in colour. Distinctive markings on the head include a dark band on top of the head between the eyes and an angled dark stripe running from the eye to the back of the jaw. The body scales are keeled resulting in a rough texture. The pupils of the eye are round, there is a protruding rostral scale on the tip of the snout. The head is small and only slightly wider than the neck. In contrast, the Western Rattlesnake has a broad, triangle-shaped head, vertical pupils and a rattle at the end of the tail.