PBackground and Aim: Routine clinical and laboratory assessments facilitate the diagnosis of erythropoietin (EPO) resistant anemia. Resistance to erythropoietin (EPO) rarely occurs in children with chronic kidney disease (CKD). It may be caused by several factors, such as poor compliance, hyperparathyroidism, malnutrition, inadequate dosages, and medication. This study was conducted to evaluate the frequency and causes of EPO resistant anemia in CKD children.Methods: This observational retrospective study was performed in Ali Asghar Children’s Hospital in 2008. Children who were treated by EPO and still had hemoglobin concentrations (Hb) below 10 g/dl or required very high erythropoietin doses (more than 150 IU/kg/week) were considered as EPO resistant anemic cases. Therefore, their data including demographic data, EPO dosage, medications, underlying diseases, mode of dialysis, and lab test results were collected from their medical records.Results: The Hb concentration was below 8 g/dl in eight cases (40%). The male to female ratio was 1.66 and the median age was 7.9 years old. The median hemoglobin concentration was 6.25 g/dL. Three patients (37.5%) were true cases of resistance in EPO (two patients had bone marrow fibrosis due to hyperparathyroidism and one had EPO Ab) while five cases (62.5%) received inadequate doses of EPO (anemia improved upon an acceptable EPO dosage).Conclusion: True resistance to erythropoisis stimulatin agent is not frequent and because of there are heterogeneous causes for Lack of appropriate response to EPO, so full investigation is needed especially complete history to find the underlying reason. Keywords: Anemia; Chronic Kidney Disease; Erythropoietin