The differential diagnosis of iron deficiency anemia and anemia caused by chronic disease should not be difficult despite the fact that distinguishing these two types may be a major clinical dillema in certain cases, especialy regarding the following treatment planning phase. We report a case of 53 year old woman who was sent to our Department of Hematology with a registered anemia (Hb 87 g/L). Although previous tests were not sufficient for establishing a clear diagnosis, iron replacement therapy had been started by general practitioner six months prior to the patients admittance to our ward. Concomitant postmenopausal vaginal bleeding, inflamatory process and possible gynecologic malignant tumor recorded in the same patient, made the diagnosing process of the primary cause of microcitic anemia quite complex. After hysterectomy which revealed no pathohystological evidence of any malignant gynecological tumor and antibiotic treatment for pelvic inflamatory disease, routine blood tests slowly normalized without iron replacement therapy and patient was in much better condition after three months follow up. We emphasize that routine laboratory analyses are not always sufficient for establishing a definitive diagnosis of the iron deficiency anemia. In cases where serum feritin level is not reliable due to its increase with age, chronic disorders and malignancy, considering a strong suspicion of iron deficiency, it is necessary to use serum transferrin receptor assay, which is not affected by chronic diseases.