The ability of healthcare-associated infections (HAIs) to form biofilms on biotic and abiotic surfaces is a major challenge. Biofilm formation explains the course of such forms of HAIs as those associated with invasive devices. At the same time, biofilm forms of microorganisms can be the cause of long-term infectious diseases that do not respond to antibiotic therapy. Objective. To identify epidemiological characteristics of HAIs caused by biofilm-forming microorganisms. Patients and methods. Microbiological, physicochemical, electron-microscopic and descriptive epidemiological methods of research were used in the work, which included assessment of the intensity and structure of the epidemic process under study, as well as determination of the etiologic structure of HAIs pathogens prone to biofilm formation. In order to analyze the epidemic process of HAIs, including HAIs associated with biofilm forms of microorganisms, a prospective study was conducted, in which three groups of patients were identified: 1) with catheter-related urinary tract infection (CAUTI); 2) with catheter-related bloodstream infection (CRBSI); 3) with surgical site infection (SSI) (periprosthetic infection). Results. The generalized incident density of CAUTIs was 6.4 per 1000 catheter-days; the incident density of CAUTIs associated with biofilm forms of microorganisms in patients with urolithiasis was 2-fold higher at 13.4 per 1000 catheter-days. In the studied group of patients with CAUTI, infections associated with biofilm-forming microorganisms accounted for 64%. The overall structure of CAUTI pathogens was represented by the following prevalent microorganisms: Escherichia coli (22.9%), Enterococcus faecalis (21.2%) and Klebsiella pneumoniae (7.6%). In the etiologic structure of pathogens of urinary tract infections (UTI) associated with biofilm forms of microorganisms in patients with urolithiasis, E. faecalis (23.8%), E. coli (22.2%) and Pseudomonas aeruginosa (12.7%) prevailed. The generalized incident CRBSI density was 3.74 per 1,000 catheter-days, while the CRBSI rate in the ICU was higher at 4.76 per 1,000 catheter-days. The proportion of CRBSI associated with biofilm forms of microorganisms in the study group was 36.6%. Staphylococcus aureus (17.8%), K. pneumoniae (15%), Staphylococcus epidermidis (14.6%) and Acinetobacter baumannii (11.7%) were predominant in the overall etiology of CRBSI. The etiologic structure of the identified biofilms in patients with CRBSI was represented by the following microorganisms: K. pneumoniae (27.3%), A. baumannii (27.3%), and S. aureus (18.4%). It was found that in the etiologic structure of trauma patients with SSI, S. aureus (64%) prevailed (64%), which has a pronounced ability to biofilm formation. Conclusion. Infections caused by biofilm forms of microorganisms account for a significant share in the structure of HAIs (CAUTI – 64%, CRBSI – 36.6%). The revealed epidemiological characteristics of HAIs caused by biofilm forms of microorganisms indicate their high prevalence and necessitate the introduction of risk-oriented methods of prevention of these infections. Key words: biofilm, biofilm forms of microorganisms, surgical site infections, healthcare-associated infections, catheter-associated bloodstream infections, catheter-associated urinary tract infections, optical density, scanning electron microscopy