Summary: The purpose of this article is to describe aspiration pneumonia (AP). One of the most important aspect of the diagnosis is the differentiation with communityacquired and health careassociated pneumonia that are not related to aspiration. The main pathomechanism of AP is macroaspiration from the oral cavity and upper respiratory tract. There are two types, that can be distinguished: infectious and chemical aspiration pneumonia. Risk factors include impaired cough reflex, swallowing disorders, gastrointestinal motility disturbance, malnutrition, probe feeding, low oral hygiene, drug poisoning, and nervous system diseases. Recently attention has been paid to a change in the etiological factors causing aspiration pneumonia. The correct collection of material for microbiological tests is important for making a proper diagnosis and the implementation of adequate antibiotic therapy.