Premature pubarche in boys is a rare manifestation of McCune-Albright syndrome (MAS). In all cases published so far, it has always been attributed to an excessive testosterone production in the testicles. For the first time we describe a boy with MAS and evidence of premature pubarche of extragonadal origin. Apart from fibrous dysplasia of the forehead and a growth hormone- and prolactin-producing pituitary adenoma, the boy presented with premature pubarche at the age of 6 years and 11 months. The size of his testicles was only 2 ml at that time and remained thus despite a progression of his pubic hair to Tanner stage IV at the age of 10 years. In the basal blood analysis testosterone was not significantly elevated. However, androstenedione and DHEAS were elevated in the serum, and in repetitive 24-hour urine samples DHEAS metabolites were markedly elevated. We therefore concluded that the patient’s premature pubarche might have originated in an increased production of DHEAS. This increased production might be due to an activating mutation of a hormone receptor in the zona reticularis of his adrenal glands leading to an increase in sulfotransferase activity and excessive DHEAS production.