Pig frog coloration is olive to blackish brown with scattered dark spots. Its venter is white or pale yellow with a pattern that is the colors brown, dark gray and black woven into a net on the thighs. The thighs also have a light line or a row of light spots running across their rear. In this frog, the tibia is the same length as the femur. Their eyes are greatly elevated and unusually large, with only a narrow space between them.
Nostrils are prominent in Rana grylio .
They have an elevated fold of skin over the ear that runs to the shoulder, and the ear is orange-brown in color with a green center. Pig frogs are sexually dimorphic in size and coloration. Males and females have similar growth rates until the snout-vent length reaches about 100mm. The male's ear is greatly larger than its eye, whereas the female's ear is equal in size to the eye. Mature tadpoles are very colorful.