In this work, we have studied the relationship between selenium an vitamin E serum concentrations, muscular pathology and lack of strength of fighting bulls during the bullfight ('lidia'). We have observed in the bulls studied, low serum selenium concentration and low enzymatic activity of the erythrocytary GSH-Px and a high correlation between serum selenium and vitamin E concentrations and miocardial and musculoesqueletic chronic lessions. It would suggest that fighting bulls go to the <<lidia>> having subclinical nutritional deficiencies what would made them prone to show a muscular weakness when they are force to make a physical effort. By the other hand, acute muscular lessions would be due to the exercise and stress of the <<lidia>>. This kind of lessions on the miocardium were more frequent in fatty bulls. Nevertheless, considering the high correlation between physical constitution, weigh and strength and that the strongest bulls fall down the less, it seems that neither acute cardiac lessions are the direct answer to the fighting bulls fall down. All these results would confirm that the lack of strength showed by fighting bulls during the bullfight is a multifactorial phenomen.