Opheodrys aestivus, commonly known as the rough green snake, is a nonvenomous North American colubrid. It is sometimes called grass snake or green grass snake, but these names are more commonly applied to the smooth green snake (Opheodrys vernalis). The European colubrid called grass snake (Natrix natrix) is unrelated. The rough green snake is docile, often allowing close approach by humans, and seldom bites.
The snake is bright green above and has a yellowish belly, affording it excellent camouflage in green vegetation. It has keeled dorsal scales. It grows up to 116 cm (45½ inches) in total length and is very thin.