This study was carried out to evaluate the effects of chronic fluorosis by means of the electrocardiograms in sheep. Ten sheep with fluorosis living around a volcanic mountain (Tendurek Mount) in East Anatolia in Turkey and 10 healthy sheep were used. Leads I, II, III, aVR, aVL, aVF, V-2, V-4, and V-10 were recorded in the electrocardiographs of the sheep. All waves were seen in all derivations. The P-Q interval was significantly (p < 0.05) prolonged and sinus bradycardia was observed in the sheep with fluorosis. As a result of this, the number of heart beats was decreased significantly (p < 0.05); that is, the number of heart beats was 110 +/- 15 in the control group and 75 +/- 10 in sheep with fluorosis.