Objective: The aim of our study is to examine the relationship between adenomyosis and chronic endometritis and to discuss its possible effects on pathogenesis. Design: Prospective analysis of previous patients’ pathology specimens Setting: A tertiary university hospital’s department of obstetrics and gynecology. Patients: Patients who underwent hysterectomy at were divided into two groups according to the presence or absence of adenomyosis. A propensity score matching analysis was performed to minimize selection bias in patient groups. A total of 146, 73 patients in each group, were included in the study. Methods: The previous specimens of the patients were re-evaluated with the CD38 immunohistochemistry staining method. A positive diagnosis of CE was made in the presence of plasma cells. In particular, basal endometrial thickness was measured in endo-myometrial transition zones. Main outcome measures and Results: The adenomyosis group was significantly younger than the group without adenomyosis (47.14 ± 4.24 vs. 50.36 ± 7.02, p = 0.012). 17 (11.6%) patients in the adenomyosis group were diagnosed with chronic endometritis, while 7 (4.8%) patients in the control group were diagnosed with chronic endometritis, and a statistically significant difference was found (p<0.05). Basal endometrium could be measured in a total of 112 (76.7%) patients, while basal endometrial loss was observed in 34 (23.3%) patients. Chronic endometritis was found in 16 (47%) of the patients with basal endometrial loss. The baseline endometrial thickness of 112 (76.7%) of the patients could be measured, but only 8 (7.1%) of them had chronic endometritis. There was a statistically significant difference between the groups (p<0.001). In multivariate analysis, there was a statistically significant relationship between basal endometrial loss and CE. Conclusion(s): A significant relationship was observed between adenomyosis and chronic endometritis.