Abstract Objective: The aim of the study was to evaluate the relationship between serum free and total PSA and histopathological findings in women with fibrocystic mastopathy. Material and methods: 176 women with fibrocystic breast disease, aged 18 to 45 years. - group I: comprised 114 patients with cysts <10mm in diameter - group II: comprised 62 women with cysts >10mm in diameter The control group consisted of 46 healthy women aged 18 - 45 years who had no breast pathology. Total PSA (PSA-T) and free PSA (PSA-Free) were measured by an ultra-sensitive fluoroimmunometric DELFIA assay (Prostatus PSA Free/Total Wallac, Turku, Finland). The detection limit for PSA was 0.01 ng/ml. Endometrial samples have been obtained with Pipelle probe between 22 and 24 days of the menstrual cycle. Results: In the control group secretory endometrium was more frequently detected than in the mastopathy group (chi2=11,15, p=0.01). Proliferatory (chi2=8.27, p=0.004) and presecretory endometrium (chi2=4.61, p=0.03) were more frequently detected in the mastopathy group than in controls. We did not find statistically significant relationship between the mean PSA concentrations between the groups in relation to histopathological findings. Conclusions: No relationships between free and total PSA measured in the follicular phase of the menstrual cycle and endometrial findings were detected in our study. Further research is required to evaluate the relationship between PSA and endometrial findings.