Objectives: To evaluate the serum level of prolidase, which is a marker of fibrogenic activity, in women with idiopathic primary ovarian insufficiency (POI). Study Design: This is a prospective case-control study. Serum prolidase level was compared between the study group including 68 women with POI and control group including 65 normally menstruating women. Serum proline and hydroxyproline levels were also compared. Correlation analyses were performed between the prolidase level and POI related parameters including estradiol (E), follicle stimulating hormone (FSH), antimullerian hormone (AMH) levels, and presence of POI family history. Results: Serum prolidase and proline level were significantly increased in women with the diagnosis of POI compared to the control group (1082.57 (147.53) vs 981.13 (223.26) U/L, 233.30 (83.16) vs 218.94 (82.59) mu mol/L, respectively). Prolidase level found to have significant correlations with AMH, E, FSH levels, and presence of POI family history (r = -0.49, p = 0.001; r = -0.39, p = 0.001; r = 0.42, p = 0.001; r = 0.22, p = 0.01; respectively). In receiver operating characteristics analysis, prolidase was shown to be a discriminative factor for POI at 1031.14 U/L cut-off value with 75 % sensitivity and 65 % specificity. The area under curve was 0.71 [(95 % CI: 0.62-0.79), p = 0.001]. Conclusion: The current study revealed increased prolidase level in women with POI. Serum prolidase level was also negatively correlated with the serum AMH level. Considering the present findings, prolidase may be a candidate molecule in assessment of POI cases.