Anemia is a common condition, but its causes are often unclear, especially in elderly adults. Erythropoietin (EPO) levels are known to be elevated in myelodysplastic syndrome and hematologic malignancies, but decreased in chronic benign anemia. This study aimed to investigate whether EPO levels could be used to identify underlying bone marrow diseases including malignancies, among elderly anemic patients with unclear etiology. This single centered retrospective study included patients presented with isolated anemia and had their EPO levels measured at their first visit. Patients were divided into two groups: bone marrow disease and benign etiologic anemia, based on observation and bone marrow test results. Out of 1180 patients reviewed, 81 patients with anemia of unclear etiology were identified, including 67 with benign anemia and 14 with bone marrow disease. Statistically significant difference in EPO levels between these two groups (P < 0.001) were observed. The receiver operating characteristic curve analysis showed that an EPO cut-off value of 36.4 mU/mL had a sensitivity and specificity of 92.8% and 94.0% for detecting underlying bone marrow disease, respectively. We suggest measuring serum EPO levels can aid in the early detection of benign anemia from bone marrow disease, including malignancies, with high sensitivity and specificity.