Background: We analyzed the incidence of acute kidney injury and chronic renal failure in chronic myeloid leukemia (CML) patients using imatinib and investigated whether there is a relation between duration of imatinib therapy and decrease in estimated glomerular filtration rate (GFR). Patients and methods: One hundred five CML patients on imatinib therapy were enrolled. Creatinine, urea, uric acid, and potassium measurements from imatinib treatment onset until the end of follow-up (median 4.5 years) were included in the analysis. GFR was estimated using the Chronic Kidney Disease Epidemiology Collaboration equation. Results: During follow-up, 7% of patients developed acute kidney injury; creatinine levels returned to baseline in only one of them. According to the regression equation, the mean baseline value of the estimated GFR was 88.9 ml/min/1.73 m(2). Estimated GFR decreased significantly with imatinib treatment duration; the mean decrease per year was 2.77 ml/min/1.73 m(2) (P < 0.001); 12% of patients developed chronic renal failure. Age, hypertension, and a history of chronic renal failure or interferon usage were not significantly related to the mean decrease in the estimated GFR over time. Conclusion: The introduction of imatinib therapy in nonclinical trial CML patients is associated with potentially irreversible acute renal injury, and the long-term treatment may cause a clinically relevant decrease in the estimated GFR.