Bacterial endocarditis on cardiac valvular prosthesis is still a frequent and dangerous complication: septicemia, embolism, valvular dysfunction and mortality. To prevent these complications, intraoperative treatment of prosthesis, by immersion in antibiotic solution, was performed in 1262 patients. The postoperative results have been compared with results of a nontreated group. The incidence of endocarditis in the treated group was 1.3%, in non-treated cases 5.45%. The cases of early endocarditis, was 0.08% of total cases of complications in the treated patients group; and 4.54% in the nontreated patient group. This study's results, confirm the utility of valvular prosthesis antibiotic treatment in cardiac surgery.