Cardiotoxicity has been feared as a potential side effect of imatinib therapy. Studies with short-term follow-up failed to identify an excess of cardiac events, but longer-term observations are needed to more definitely exclude this adverse effect. This study was designed to assess the cardiac effects of imatinib in patients under long-term treatment. We included 90 chronic myeloid leukaemia (CML) patients under imatinib therapy for a median treatment time of 3.3 years (mean age 48.9 +/- 15.1 years). Patients underwent clinical evaluation, electrocardiography, echocardiography (two-dimensional, colour flow, tissue Doppler and strain imaging), brain natiuretic peptide (BNP) and troponin I measurements. Twenty healthy volunteers were included as a control group for strain measurements. The mean ejection fraction was 68 +/- 7% and the median BNP level was 9.6 pg/ml (interquartile range [IQR] 5.7-17.0 pg/ml). Two patients had either an elevated BNP or a depressed ejection fraction (2.2%; 90% CI 0.9-6.8%). Most of troponin I measurements were lower than the detection limit, except for two patients. Longitudinal strain was similar to measurements in healthy controls. A weak relation was observed between log BNP and imatinib treatment duration and dose. There was no relation between these variables and left ventricle ejection fraction. In conclusion, matinib-related cardiotoxicity is an uncommon event in CML patients, even during long-term treatment. Therefore, its use should not be cause of great concern, and the usefulness of regular cardiac monitoring all patients while on imatinib therapy is questionable. Copyright (C) 2010 John Wiley & Sons, Ltd.