Several studies have looked at populations of volunteers, women from the electoral roll and women attending general practices, and have reported the ultrasound appearance of polycystic ovaries in as many as one in three to one in five. If groups of women with irregular periods are looked at, up to 90% will have polycystic ovaries at ultrasound. Similarly, when women with increased facial and body hair are screened, about 90% will have polycystic ovaries, as will three out of four women with acne. It has also been suggested by some studies that women with recurrent miscarriage or early pregnancy loss after in-vitro fertilization have an increased incidence of polycystic ovaries. However, not all studies support this hypothesis, and additional research is needed to evaluate this further. A Guide to the Polycystic Ovary looks at the historical background of this condition; the structure and function of the female genital organs; symptoms and signs; diagnostic techniques; the inheritance of polycystic ovary syndrome; long-term effects; lifestyle factors; polycystic ovaries and the skin; ovulation induction; surgical treatment to induce ovulation; in-vitro fertilization; pregnancy outcomes.