Adenomatoid tumor (AT) is a benign neoplasm that originates from mesothelial cells, occurring in the female and male genital tracts although a limited number of cases have also been observed in extragenital sites such as the adrenal gland. In fact, the English literature only records approximately 40 cases of adrenal AT so far. Here we report a case of adrenal AT occurring in male patients aged 45 years who was admitted to the hospital because of mild left back pain and hypertension. The patient then underwent multislice computed tomography (MSCT) scan, detecting a tumor in the left adrenal gland. Histologically, the tumor in the adrenal gland was composed of growth patterns including microcysts, tubules, macrocysts and anastomosing structures lined by endothelial-like cells which were flattened and bland with no appreciable mitoses. Lymphoid aggregates and interspersed lymphocytes were frequently present. Immunohistochemically, the tumor cells were positive for mesothelial markers (calretinin, D2-40, and WT-1) and negative for CD31. Adenomatoid tumor is an extremely rare neoplasm in the adrenal gland which is morphologically and immunophenotypically identical to that occurring in the genital tracts. Immunohistochemical profiles play a pivotal role in reaching the diagnosis of this benign tumor, helping to avoid misdiagnosis and overtreatment.