Objective. To study the possibility of the 2D Speckle Tracking Imaging in early detection of cardiotoxicity in patients with triple negative breast cancer and arterial hypertension (AH) during anthracycline-containing chemotherapy. Materials and methods. 70 women (mean age 48.6±13.3 years) with triple negative breast cancer were enrolled. All patients underwent chemotherapy, including anthracycline, taxan, platinum-based agent. Echocardiography, including 2D Speckle Tracking Imaging, was performed on Vivid-E 9 ultrasound machine before and after 8 weeks of chemotherapy. Left ventricular ejection fraction (LVEF) (the biplane Simpson`s method) and global longitudinal strain (GLS) (mean normal GLS of -22.1±1.8 for women) were analysed. Patients were divided into two groups: group 1 – with AH (n=18) and group 2 – with normal blood pressure (n=52). Results. Before chemotherapy in group 1 GLS was lower than normal value (-19.1±2.8% vs -22.1±1.8%; p<0.05) and lower than in the group 2 (-19.1±2.8% vs -20.0±2.8%; p>0.05). After chemotherapy in all patients GLS decrease was observed from -20.0±2.8% to -18.5±2.9% (p<0.05) and in group 1 from -19.1±2.8% to -16.4±3.8% (р<0.05), group 2 from -20.0±2.8% to -19.2±2.4% (p<0.05). However LVEF remained within normal values. The values of GLS decreased by more than 15% in 12 (17%) of all the patients. Conclusions. Apparently, GLS is the one of most sensitive early marker of chemotherapy – induced cardiotoxicity compared with the LVEF.