Aim: The objective of this study was to compare classical blind endometrial tissue sampling with hysteroscopic biopsy sampling following methylene blue dyeing in premenopausal and postmenopausal patients with abnormal uterine bleeding. Material and Methods: A prospective case-control study was carried out in the Office Hysteroscopy Unit. Fifty-four patients with complaints of abnormal uterine bleeding were evaluated. Data of 38 patients were included in the statistical analysis. Three groups were compared by examining samples obtained through hysteroscopic biopsy before and after methylene blue dyeing, and classical blind endometrial tissue sampling. First, uterine cavity was evaluated with office hysteroscopy. Methylene blue dye was administered through the hysteroscopic inlet. Tissue samples were obtained from stained and non-stained areas. Blind endometrial sampling was performed in the same patients immediately after the hysteroscopy procedure. The results of hysteroscopic biopsy from methylene blue stained and non-stained areas and blind biopsy were compared. Results: No statistically significant differences were determined in the comparison of biopsy samples obtained from methylene-blue stained, non-stained areas and blind biopsy (P > 0.05). Conclusions:We suggest that chromohysteroscopy is not superior to endometrial sampling in cases of abnormal uterine bleeding. Further studies with greater sample sizes should be performed to assess the validity of routine use of endometrial dyeing.