Polycystic ovarian syndrome (PCOS), first described in 1937, was defined by specific ovarian histopathology and a constellation of signs and symptoms. Through the years, the etiology remained elusive, with heated debates focusing in turn on the ovary and then the pituitary as the causative agents. In the last several decades, it has become clear that insulin resistance makes up a very important component of this syndrome. With this knowledge, new therapies have emerged along with the realization that PCOS and the metabolic syndrome are closely related through their shared insulin resistance. In this review, the diagnosis, pathophysiology, and therapy of PCOS are discussed and upon this background, those areas held in common by PCOS and the metabolic syndrome are explored.