The aim of this study was to use echocardiographic techniques to determine the possible cardiotoxic effects of low molecular weight tyrosine-kinase inhibitors (TKI) in patients receiving the therapy for the first time. Thirty patients (17 females; 13 males; mean age 49±16; range 22 to 76 years) who met the exclusion criteria and were diagnosed as having malignancy were enrolled. All patients underwent conventional echocardiography and tissue Doppler imaging (TDI) prior to the treatment. The conventional echocardiogram was repeated 2 months later as the patients were concurrently receiving therapy. Myocardial Performance Index was obtained by conventional echocardiography and by TDI techniques to evaluate left ventricular systolic and diastolic function. Statistically significant increase occurred in mean left ventricle (LV) end-systolic volume. However, there was significant decrease in both mean LV ejection fraction and LV stroke volume values (64±3, 62±4, p=0.000 and 67±13, 61±13, p=0.000, respectively). Anterior wall Em/Am ratio measured by using the TDI technique was significantly decreased at the end of two months (0.99±0.49, 0.90±0.41, p=0.03). In addition, decreases were determined in Sm values obtained from all of four LV walls and also in mean Sm value, but this decrease was significant only for the lateral wall Sm measurement (12.8±2.9, 11.6±2.3, p=0.004). Tyrosine-kinase inhibitors therapy can be administered safely to patients without predisposing factors for cardiotoxicity in short treatment intervals, and low molecular TKIs may cause subtle or clinically significant cardiotoxicity following the treatment period even in patients without predisposing factors for cardiotoxicity, so clinicians should consider this possibility.