question: Clinical data available on coinfections are contradictory concerning both the number of viruses involved and the severity of the condition. A total of 114 patients aged 0–59 months with symptoms of respiratory tract infection were enrolled into the study. Nasal and pharyngeal swabs were tested using the PCR method for the following 12 viruses: influenza A, influenza B, respiratory syncytial virus A (RSV A), respiratory syncytial virus B (RSV B), adenovirus, metapneumovirus, coronavirus 229E/NL63 (hCoV229), coronavirus OC43 (hCoVOC43), parainfluenza virus 1 (PIV-1), parainfluenza virus 2 (PIV-2), parainfluenza virus 3 (PIV-3), and rhinovirus A/B. Coinfections were detected in nine (8 %) patients. Five of the coinfections were related to influenza A (H3N2) virus associated with the following other, single or combined, respiratory viruses: influenza B in one case, hCoV229 in two cases, hCoV229, RSV A, and PIV-2 in one case, and PIV-1, PIV-2, RSV A, RSV B, and adenovirus in one case. The other four coinfections were caused by: adenovirus and hCoVOC43, adenovirus, and rhinovirus, RSV A and PIV-1, influenza B, and RSV B. We did not observe any significant differences in the clinical course of infections caused either by a single or multiple viral factors.