Background The addition of rituximab to doxorubicin-containing standard chemotherapy significantly improves response to therapy and reduces the risk of death in B-cell non-Hodgkin's lymphoma (NHL) patients. However, the impact of this approach on doxorubicin-induced cardiotoxicity has not been elucidated. Methods Patients who had been planned to receive CHOP or rituximab plus CHOP (R-CHOP) combination chemotherapy with a diagnosis of NHL were included in the study. In all patients, systolic and diastolic parameters were measured by using conventional and pulsed-wave tissue Doppler echocardiography, which is more sensitive than conventional lead-dependent techniques, both before and in the sixth month of therapy. Results There were 28 (M/F; 14/14) patients on CHOP and 33 (M/F; 16/17) patients on R-CHOP. Median age in CHOP and R-CHOP was 49 and 50 years (P = 0.44), respectively. Cumulative doxorubicin doses were 280 and 286 mg/m2 on CHOP and R-CHOP (P = 0.65), respectively. None of the patients developed clinically evident congestive heart failure. Parameters of systolic function such as LVEF and FS did not significantly change in any patients. In both arms, tissue Doppler parameters of diastolic function such as lateral E and septal E velocity of mitral annulus decreased significantly after therapy (P < 0.001). However, the decrease in diastolic function was similar in both arms (P > 0.05). Conventional Doppler echocardiography yielded consistent findings. Conclusion Both CHOP and R-CHOP cause diastolic dysfunction in the early period following their administration. The addition of rituximab to CHOP chemotherapy does not significantly increase the risk of doxorubicin-induced cardiotoxicity during this period.