The so-called zoonotic endocarditis is transmitted from animals to humans and is frequently found in some cattle-raising countries. Brucella endocarditis is a destructive process of the aortic valve with abscess formation that commonly leads to heart failure. Q fever endocarditis is a more indolent infection, but it is also capable of producing severe valvular damage and hemodynamic compromise. Treatment of zoonotic endocarditis includes the prolonged administration of doxycycline in combination with other antimicrobial agents and a judicious use of valve replacement. Mortality of Brucella endocarditis has been decreased significantly by a medical-surgical approach to treatment. On the basis of serologic and valve tissue culture results, no treatment is consistently able to cure Q fever endocarditis, and thus mortality of this infection remains high.