Aim. To analyze in-hospital infection in oncology center within 2012—2016. Material and methods. There were 98 patients with nosocomial infection who underwent surgery for malignancies. Microbiological examination of biological materials was carried out by appropriate laboratories according to generally accepted methods. Results. Mono- and polymicrobial infection was observed in 58 and 42% of cases. Staphylococcus aureus was the most common agent in patients with microbial infection. Minimal inhibitory concentration of vancomycin (MIC) ≥1.0 μg/ml was revealed in 60% of microbes. Microbial agents isolated were resistant to antibacterial drugs used to prevent postoperative infectious complications. Conclusion. In-hospital infection was accompanied by staphylococci as a rule. Causative agents of nosocomial infections are usually resistant to conventional antibacterial drugs. Moreover, 60.1% of microbes had minimal inhibitory concentration of vancomycin ≥1.0 μg/ml that indicated the need for alternative therapeutic agents.