CAP is divided to two principal groups: Bacterial CAP and Atypical CAP. Since pathogens are different, treatment approach is also different. The main obstacle is absence of adequate diagnostic immediate and cheap tools to enable identifying pathogen and hence treatment is not always appropriate. Giving the right therapy at the right time is of major importance since early start of correct treatment is linked to morbidity and mortality of patients. For prescribing appropriate empiric therapy, knowing the epidemiology of CAP, i.e. the frequent causing pathogens according to age groups and other demographic characteristics, is essential.