Abstract: AIM:To assess the value of two-dimensional speckle tracking imaging (STI) in detecting early damage of left ventricular function in breast cancer patients treated with different doses of anthracycline. METHODS: Sixty-two female breast cancer patients were selected and were administered a six-cycle epirubicin-based chemotherapy. The systolic strain rate (SRs), early diastolic strain rate (SRe) and later diastolic strain rate (SRa) of left ventricular basal segments and the parameters of conventional echocardiography were measured 1 day before and the third day after each chemotherapy session and a self-control study of the parameters was conducted. RESULTS: Conventional echocardiography showed that the cumulative dose at the fifth-cycle chemotherapy and the sixth-cycle chemotherapy was, respectively, 450 mg/m2 and 540 mg/m2, and E/A was significantly reduced compared with that before chemotherapy (P<0.05). STI showed that at the third-cycle chemotherapy, the cumulative dose was 270 mg/m2 and SRe and SRa of left ventricular basal segments began to decrease (P<0.05). SRe and SRa reduced significantly at the fifth-cycle chemotherapy and the sixth-cycle chemotherapy (P<0.01) as well as the reduction of SRs (P<0.05). CONCLUSION: During chemotherapy, SRI changes appear earlier than those of conventional echocardiography. Therefore, STI is more sensitive in detecting early damage of left ventricular function caused by anthracycline in breast cancer patients.