Alarin is a newly identified peptide hormone. It is implicated that alarinplays roles in regulation of energy metabolism and hypothalamo-pituitary-gonadal axis. Polycystic Ovary Syndrome (PCOS) is a common reproductive and metabolic disease in women during reproductive ages. Over-secretion of Luteinizing Hormone (LH) causes hyperandrogenism in women with PCOS. The purpose of the study was to determine the comparison of alarin levels in women with or without PCOS as well as to investigate the relationship between alarin and LH. Eighty-four women with PCOS and 84 age- and BMI- matched controls were recruited in this cross-sectional study. Circulating alarin levels were assessed via ELISA method. The hormonal and metabolic parameters of the recruited subjects were also determined. The circulating levels of alarin in PCOS subjects were higher than controls (6.11 ± 1.91 vs. 3.93 ± 1.60 ng/ml, P <0.001). Alarin showed a positive correlation with insulin resistance marker, BMI, LH and androgens. Moreover, alarin levels were elevated in women with PCOS having insulin resistance compared to those PCOS women without insulin resistance. In both control and PCOS groups, overweight subjects showed an elevation in circulating levels of alarin with respect to normal weight subjects. In the present study, Alarin level with the highest tertile dosage comparing to alarin level with the lowest tertile dosage could highly increase the probability of PCOS risk prevalence in women. Elevated alarin levels in women with PCOS were associated with not only LH and metabolic parameters but also high probability of having PCOS risk independently.