Too often still this disease is called sacrococcygeal cyst, pointing into the direction of congenital etiology. With this paper (and a review of the literature) we try to proof that the theory of acquired origin of pilonidal sinus is the only one logically to be accepted. We indicate that extensive surgical procedures such as Z-plasty rotated flap or broad excision--are really unnecessary and that a simple and accurate technique--marsupialization--gives excellent results with a minimum of recurrences. The last few years phenolization of the pilonidal sinus has become a popular, and eventually a worthwhile alternative.