Polycystic ovary syndrome (PCOS) is the most common endocrinopathy affecting women of reproductive age and is increasingly recognized as a disorder manifesting in the peripubertal and adolescent period. Diagnosis in the adolescent is difficult due to the high background rate of menstrual irregularity, the high prevalence of polycystic ovarian morphology and hyperandrogenic features in this population. Recent guidelines suggest that menstrual irregularity for over two years, reduced reliance on ultrasound diagnosis of polycystic ovarian morphology, and accurate assessment of hyperandrogenic and metabolic features are suitable strategies for the diagnosis of PCOS in the adolescent. Accurate diagnosis is important given the long-term implications of the disorder, with increasing emphasis on metabolic sequelae.