This paper aim is to outline the importance of nosocomial infections, characterized by great incidence, great mortality rate and specific bacteriology, in a surgery clinic. The study include 566 patients that developed 665 nosocomial infections (10.65% incidence), among the 5950 patients that underwent surgical operations in 5 years (1992-1996); 54 patients developed two or three nosocomial infections, which explain the incidence of nosocomial infection greater than number of patients. From bacteriological point of view predominance of Gram negative bacilli (especially E. coli) and pathogen staphylococcus characterized the nosocomial infections. The infection source was the patient himself, previously colonized with hospital specific microorganisms. Every clinical form of nosocomial infections was characterized by the present of specific pathogen microorganisms; the knowledge of these pathogen agents is very important for the antibiotic treatment applied before the bacteriological exam.