Otitis media is a multifactorial disease. It represents a major public health burden, as it is the most common diagnosis in children and is characterized by both immediate and long-term morbidity. For years the knowledge about risk factors and microbiology of otitis media has been relatively stable. In recent years new data have been gathered regarding different microbiological aspects of otitis media. This new knowledge may contribute toward the development and implementation of therapeutic and preventive strategies.