Aim: Galectin-3 (Gal-3) plays a role in modulation of adiposity, glucose hemostasis and inflammation. The association between Gal-3 and the polycystic ovary syndrome (PCOS), is not investigated. We aimed to evaluate galectin-3 levels in serum and their relation with hyperandrogenism and insulin resistance (IR) in women with polycystic ovary syndrome (PCOS) and in control subjects. Materials and methods: 56 women with PCOS were enrolled along with a control group of 41 healthy women, matched for age and body mass index. We measured hormonal and metabolic parameters, as well as the serum galectin-3 concentration of each participant. We estimated the IR according to the homeostasis model assessment-insulin resistance (HOMA-IR). Results: Women with PCOS had higher levels of serum Gal-3 compared to healthy individuals (3,588.77 ± 1,566.94 vs 2,491.33 ± 812.04, P < 0.001). Serum Gal-3 levels were correlated with progesterone (r = 0.241, P = 0.025), hirsutism score (r = 0.296, P = 0.006), insulin (r = 0.479, P = 0.028), HOMA-IR (r = 0.514, P = 0.017), dehydroepiandrosterone sulfate (r = 0.246, P = 0.022), testosterone (r = 0.252, P = 0.019), and free testosterone (r = 0.306, P = 0.004). Conclusion: Galectin-3 levels are higher in patients with PCOS, and there is a positive correlation between galectin-3 level and IR, androgen levels and hirsutismus scores. Gal-3 may be a new mediator of PCOS via IR, hyperandrogenism. © Italian Society of Endocrinology (SIE) 2013.