B-cell lymphoma-2 (BCL-2) is an anti-apoptotic protein that may play a role in disordered proliferative endometrium (DPE) and endometrial hyperplasia (EH). Several studies have investigated BCL-2 expression in normal, hyperplastic endometrium and endometrial adenocarcinoma, with conflicting results. Therefore, the present study aimed to compare the expression of BCL-2 in disordered proliferative endometrium and simple EH. In this cross-sectional study, 63 DPE and 67 SEH samples from patients referred to Mostafa Khomeini Hospital between 2017 and 2022 were immunohistochemically stained by BCL-2 antibody. BCL-2 expression in each sample was reported as negative, weak positive, and strong positive. The findings were analyzed using SPSS version 16 software. Negative, weakly positive, and strongly positive BCL-2 expression was observed in 55.6%, 38.1%, and 6.3% of DPE samples, and 61.2%, 31.3%, and 7.5% of SEH samples, respectively, which does not show a statistically significant difference (p=0.718). There was no relationship between the age of patients and BCL-2 expression in any of the two groups of DPE and SEH (p=0.378 and p=0.178, respectively). BCL-2 expression is observed with a relatively similar frequency in DPE and SEH samples, and it is probably under the control of oestrogen hormone as the main factor involved in the pathogenesis of these lesions.