BACKGROUND: M. pneumoniae is a common cause of respiratory tract infections (RTIs) of variable severity especially in children. New diagnostic techniques offered more reliable information about the epidemiology of infection by this pathogen.AIM: The aim of this study was to investigate the prevalence and epidemiology of acute M. pneumoniae infections among Greek children hospitalized for RTIs using more advanced techniques.MATERIAL AND METHODS: The study included 225 Greek children hospitalized for RTIs during a 15-month period. Throat swab specimens were tested by PCR for the detection of M. pneumoniae, while IgG and IgM antibodies were determined by ELISA and, in certain cases, also by western-blot. In parallel, specimens were tested for the presence of additional respiratory pathogens.RESULTS: M. pneumoniae infection was diagnosed as the only pathogen in 25 (11.1%) cases, being the second (after respiratory syncytial virus- RSV) most often detected pathogen. The proportion of cases with M. pneumoniae infection in age group 8-14 years (23.3%) was significantly higher than that in <3 years age group.CONCLUSION: During our study period, M. pneumoniae was the second causative agent of RTIs after RSV. The proportion of children with M. pneumoniae RTIs increased with age, while most cases were reported during summer and autumn.