In this article there are given results of microbiological investigation of nosocomial pneumonia agents, microbial structure. Investigation was held in 727 cases of traumatological patients treated because of hip replacement or osteosinthesis of limbs. Complications with nosocomial pneumonia was found in 27 cases (3,7%). In 27 cases of diagnosed pneumonia, 66 microbial strains were isolated. In 4 cases (14,8%) was detected mono infection, different microbial association were isolated in 23 cases (85,2%) - 2 microbes in 7 and 3 microbes in 16 cases. Microbial structure was presented by: S.aureus (27,3%), Kl.pneumoniae (19.7%), S. pneumoniae (15,2%), A. baumanii (10,6%), E. coli (4,6%), enterobacter spp. (9,1%), P. aeruginosa (13,6%). Study of sensitiveness/resistance of separated stains to different groups of antibiotics showed, that micro organisms have high level of resistance to antibiotics and also pan-resistance. So, success of antimicrobial therapy depends on prompt and correct choice of antibiotics, based on aetiology of infection and sensitiveness to antibiotics. In cases of empirical administration, it is necessary to use antibiotics with high level of activity against pneumonia agents - carbapenems, and in case of high probability of MRSA - it is better to use linezolid or vancomicin.