Background: Doxorubicin is a chemotherapeutic agent used in a wide spectrum of cancers. However, cardiotoxic effects have limited its clinical use. The early detection of doxorubicin-induced cardiotoxicity is crucial. The purpose of our study was to assess values of Doppler and tissue Doppler imaging (TDI)-derived myocardial performance index (MPI) in adult cancer patients receiving doxorubicin treatment. Methods: A total of 45 patients underwent echocardiographic examinations before any doxorubicin had been administered and then after doxorubicin. Doppler and TDI-derived MPI of left ventricular (LV) were determined in the evaluation of cardiotoxicity. Additionally, TDI-derived MPI of right ventricular (RV) was determined. Results: All patients underwent control echocardiographic examination after mean 5 ± 1.7 months. The LV MPI obtained by both Doppler and TDI were increased after doxorubicin treatment (0.56 ± 0.11, 0.61 ± 0.10, p = 0,005 vs 0.51 ± 0.09, 0.59 ± 0.09, p = 0.001, respectively). There was no correlation between Doppler-derived MPI and cumulative doxorubicin dose (coefficient of correlation 0.11, p = 0.6). TDI-derived MPI was correlated with cumulative doxorubicin dose (coefficient of correlation 0.35, p = 0.015), but this correlation is weak (r = 0.38). The study population was divided into two groups according to doxorubicin dose (below and above 300 mg level). There was a moderate correlation between TDI-derived MPI and less than 300 mg of doxorubicin dose (coefficient of correlation 0.51, p = 0.028). However, Doppler-derived MPI was not correlated with less than 300 mg of doxorubicin dose (coefficient of correlation 0.38, p = 0.123). Also, there was no significant change in the TDI-derived RV-MPI (0.49 ± 0.14, 0.50 ± 0.12, p = 0.56). Conclusions: TDI-derived MPI is a useful parameter and an early indicator compared with Doppler-derived MPI in the detection of cardiotoxicity during the early stages. Also, doxorubicin administration does not affect RV function. © 2012 Via Medica.