Brucella endocarditis is an underdiagnosed, fatal complication of human brucellosis. Four successfully treated cases of Brucella endocarditis are reported. The development of a new valvar lesion and bulky vegetations seen on echocardiography helped to identify Brucella endocarditis occurring during systemic brucellosis. The aortic valve was affected in all four patients, and in one the mitral valve was also affected. Medical treatment did not cure the patients and all needed valve replacement--for haemodynamic deterioration in three and because a further embolism was feared in one. Antibiotics were continued for six to nine months after operation. There was no early or late mortality and no recurrence after a follow up of 15 months.