A sacral dimple or presacral dimple is an indentation or pit in the skin on the lower back. A sacral dimple is congenital and present at birth. It is located just above the crease between the two folds of the buttock. Pilonidal sinus is considered an acquired condition and the diagnosis is based on identifying a characteristic epithelial track (the sinus) located in the skin of the natal cleft. This chapter discuss the clinical features, etiology, and treatment of presacral dimple and pilonidal sinus.