SUMMARYIn 1935 the pathology of polycystic ovarian sydrome (PCOS) was described by Stein and Leventhal. It is a clinical syndrome consisting of menstrual irregularities featuring amenorrhea, oligomenorrhea, infertility, masculine type hirsutism and obesity. Since that time many theories have been postulated for the pathology causing the disorder. In the meanwhile and because of the uncertainty of the underlying etiology, many treatment protocols, surgical and medical have been recommended to control that disorder.Pathophysiology:• Endocrinologic abnormalities:o Hyperandrogenic state manifested with high serum levels of testosterone, androstenedione, and DHEA-S.o High levels of (LH) leading to increased stimulation of the ovarian theca cells causing increase the production of androgens.o Lower level of FSH, which lead to inability of the ovarian granulosa cells to aromatize the androgens to estrogens, leading to decreased estrogen (Estradiol) levels and consequently anovulation.o The more important from diagnostic point of view is the high LH/FSH ratio; higher than 2.o Hyperinsulinemia: There is high levels of IGF-1 which increase insulin resistance that in turn lead to hyperinsulinemia. The latter causes dyslipidemia and elevated levels of PAI-1 in patients with PCOS . Elevated PAI-1 levels constitute a risk factor for intravascular thrombosis.* Pathologic appearance:Polycystic ovaries are enlarged bilaterally with smooth-thickened capsule. On cut section, subcapsular follicles in various stages of atresia are seen in the peripheral part of the ovary. The most striking feature of the PCOS ovary is the hyperplasia of the theca stromal cells surrounding arrested follicles. On microscopic examination, luteinized theca cells are seen.* Clinical Picture:o Menstrual Abnormalities.o Infertility due to the associated ovulation abnormalities.o Hyperandrogenism: Hirsutism and acne.o Obesity: Present in 45% of cases, it is android type of obesity with increased waist hip ratio.* Ultrasonic findings:Increased size of ovaries greater than one-half of the diameter of the fundus of the uterus with peripherally oriented cystic structures (more than 8) and each is less than 9mm in diameter with no dominant follicles seen. However; the ultrasonic picture alone is not enough for the diagnosis of PCOS as this picture was seen in normal women with Polycystic appearing ovaries.* Laboratory Findings:o High LH and increased LH/FSH ratio, very diagnostic.o Elevated androgen levels of Testosterone and dehydroepiandrosterone and Androstenedioneo Normal serum estradiol and increased serum estrone concentrations leading to Low Estradiol/Estrone ratio.o About 35% of obese PCOS have impaired glucose tolerance and 10% have type 2 diabetes mellitus .Treatment Protocols:• General: weight loss is important the prospects of both spontaneous and drug induced ovulation and also ,decrease risk of obstetric complications.• Infertility Treatment: All anovulatory women deserve at least some preliminary evaluations to exclude important pathology and at least one screening semen analysis should be always obtained.- Clomiphene Citrate (CC)? It is the first line agent used for ovulation induction in PCOS.? Dose(50-100 mg daily starting on the fifth day of the menstrual cycle and given for 5 days). The dose > loomg dialy rarely confes any advantage and can cause thickening of cervical mucous that impede passage of spernatoza .Sometimes combination of CC with metformin or other PCOS treatment may be useful .