In this study, we aimed to investigate serum and follicular fluid (FF) secreted frizzle-related protein-5 (Sfrp-5) levels in nonobese, nonhyperandrogenic patients with polycystic ovary syndrome (PCOS) undergoing in vitro fertilization (IVF), in addition to IVF outcomes. In total, 160 patients undergoing IVF treatment were included in the study: 80 patients diagnosed with PCOS according to the Rotterdam criteria (group I, study) and 80 patients with the etiology of male factor infertility (group II, control). There were statistically significant between-group differences in serum estradiol (E 2 ) levels on the day of hCG administration (2377.00 ± 733.23 vs. 1931.3 ± 1,010.69), the total gonadotropin dose required (2000.63 ± 1,051.87 vs. 1.134.69 ± 286.45), and the total number of retrieved oocytes (8.60 ± 2.06 vs. 11.05 ± 4.39) ( p  < 0.05). There was also a statistically significant between-group difference in serum and FF Sfrp-5 levels on the day of oocyte retrieval (11.40 ± 2.88 vs. 8.87 ± 1.85, p  < 0.001; 11.06 ± 2.30 vs. 9.71 ± 2.15, p  = 0.008; respectively). However, there were no between-group differences in fertilization rates, clinical pregnancy rates, and live birth rates ( p  > 0.05). A correlation analysis showed that serum and FF Sfrp-5 levels were associated with insulin and inflammatory markers ( p  < 0.05). In a selected population of nonobese, nonhyperandrogenic PCOS patients, there was a significant difference in Sfrp-5 levels of the PCOS group versus those of the control group. Further studies are needed to determine the effects of Sfrp-5 in women with PCOS.