Cardiotoxicity is the most important complication in patients receiving anthracycline chemotherapy. We studied the left ventricular diastolic function (LVDF) and systolic function (LVSF) in these patients and assessed whether LVDF deteriorates earlier than LVSF. We prospectively studied 58 patients (mean age 48.02 ± 13.87; 32 female, 26 male) on anthracycline treatment, before chemotherapy (S0) and after cumulative doses of 139 ± 12 mg/m(2) (S1) and 308 ± 14 mg/m(2) (S2). The LVSF was computed in terms of left ventricular ejection fraction (LVEF) from equilibrium radionuclide angiography (ERNA). The peak ejection rate (PER), peak filling rate (PFR), time to peak ejection rate (TPER), time to peak filling rate (TPFR), 1/3rd filling fraction and ratio of PFR and PER were calculated from ERNA and were also standardized using 150 baseline ERNA studies. Statistical analysis was done by repeated measures analysis of variance (ANOVA). We found significant decrease in LVEF (P<0.001) and PER (P<0.001) between the S1 and S2 studies and PFR (P<0.007) between the S0 and S1 studies. In conclusion in patients receiving anthracycline treatment, LVDF deteriorates earlier than left ventricular systolic function (LVSF).