Objective: To investigate the expression of interleukin- 8 (IL- 8) receptors CXCR1 and CXCR2 in adenomyosis. Design: Comparative immunohistochemical study. Setting: Academic medical center. Patient(s): Thirty women who had undergone hysterectomy and were proved histopathologically to have adenomyosis, and 27 women without adenomyosis who had a hysterectomy for nonendometrial pathology such as leiomyomata or benign ovarian cysts. Intervention(s): Tissue sections were immunostained with murine monoclonal anti- human CXCR1 and CXCR2 antibodies. Main Outcome Measure(s): Microscopic evaluation to assess the presence and localization of CXCR1 and CXCR2 throughout the menstrual cycle in both eutopic endometrial and adenomyotic tissues of women with adenomyosis and compare it with normal endometrium. Result(s): In eutopic endometrium of women with adenomyosis, proliferative phase samples showed higher epithelial CXCR1 and CXCR2 staining intensity compared with proliferative phase samples of normal endometrium. Adenomyosis foci expressed higher epithelial CXCR1 compared with the homologous eutopic endometrium and normal endometrium. On the other hand, adenomyosis foci and the homologous eutopic endometrium showed similar epithelial CXCR2 staining intensity, and this expression was higher than the normal controls. Conclusion(s): Intrinsic abnormalities concerning IL- 8 and its receptor system may be present in the eutopic endometrium of women affected by adenomyosis. These findings suggest that IL- 8 receptors may be involved in the pathogenesis and/or pathophysiology of adenomyosis. Objective: To investigate the expression of interleukin-8 (IL-8) receptors CXCR1 and CXCR2 in adenomyosis. Design: Comparative immunohistochemical study. Setting: Academic medical center. Patient (s): Thirty women who had undergone hysterectomy and were proved histopathologically to have adenomyosis, and 27 women without adenomyosis who had a hysterectomy for nonendometrial pathology such as leiomyomata or benign ovarian cysts. Intervention (s): Tissue sections were immunostained with murine monoclonal anti- human CXCR1 and CXCR2 antibodies. Main Outcome Measure (s): Microscopic evaluation to assess the presence and localization of CXCR1 and CXCR2 throughout the menstrual cycle in both eutopic endometrial and adenomyotic tissues of women with adenomyosis and compare it with normal endometrium. Results (s): In eutopic endometrium of women with adenomyosis, proliferative phase samples showed higher epithelial CXCR1 and CXCR2 staining intensity compared with proliferative phase samples of no On the other hand, adenomyosis foci and the homologous eutopic endometrium were found to be more epithelial CXCR2 staining intensity, and this expression was higher than the normal controls. Conclusion ( s): Intrinsic abnormalities concerning IL-8 and its receptor system may be present in the eutopic endometrium of women affected by adenomyosis. These findings suggest that IL-8 receptors may be involved in the pathogenesis and / or pathophysiology of adenomyosis.