In this study, 20 New Zealand rabbits were used to observe the acute toxic effect of fluoride on the heart by using echocardiographic methods. At the beginning, some echocardiographic parameters of the animals were measured without giving fluoride in order to get the control values. After this, the rabbits were equally divided into two groups as 10 and 40 mg/kg b.wt. fluoride (as sodium fluoride) were given to these groups by adding to drinking water for 15 days. The measured echocardiographic parameters from the control and experimental groups were as follows: left ventricular internal diameter in diastole and systole (LVIDD and LVIDS), left ventricular posterior wall thickness in diastole and systole (LVPWD and LVPWS), interventricular septum thickness in diastole and systole (IVSTD and IVSTS), diastolic and end systolic volume (EDV and ESV), stroke volume (SV), fractional shortening (FS) and ejection fraction (EF). Statistical comparisons among the groups were accomplished by using Anova and Duncan test.