A major problem in the treatment of leukemia is the development of resistance to chemotherapeutic agents. Assessing the drug resistance of leukemic cells is therefore an important aspect of treatment. One of the main mechanisms of resistance is rapid drug efflux mediated by various members of the ATP-binding cassette transporter superfamily, such as multidrug resistance gene 1 (MDR1), which encodes P-glycoprotein, multidrug resistance-associated protein (MRP) 1 and lung resistance protein. To quantify the degree of acquisition of resistance, several techniques, including drug-sensitivity studies, flow cytometry assay and quantitative gene analysis, have been developed to detect MDR1 and MRP1 gene expression in leukemic cells. However, a significant number of patients may relapse in spite of low expression of MDR1 or MRP1, suggesting the involvement of other intracellular mechanisms, possibly related to cytarabine resistance. This review focuses on the methods aimed at the assessment of drug resistance in acute myeloid leukemia.