Polycystic ovary syndrome (PCOS) is the most frequent endocrinopathy in reproductive-aged women. The majority of hirsute patients are diagnosed with PCOS. Hyperandrogenemia, central obesity and insulin resistance may protect patients with PCOS from osteoporosis, whereas increased cortisol levels, low growth hormone and amenorrhea may be associated with decreased bone mineral density (BMD). Recent studies suggested that insulin resistance in PCOS is associated with decreased vitamin D levels that could not be explained by obesity alone. Vitamin D treatment may therefore have positive effects on insulin sensitivity and perhaps also hyperandrogenemia in patients with PCOS. In the present article, we review the evidence of changed BMD, bone mineral turnover and vitamin D status in PCOS and hirsutism compared with healthy women and the effects of medical intervention on BMD in PCOS.