Basic research of pneumonia has been made from many aspects, and it has yielded many findings. To clarify the pathophysiology of pneumonia and the virulence of respiratory pathogens, an establishment of animal experimental models using mice and other animals is essential. Thus far, animal models of pneumonia in accordance with various pathogens have been reported, including Streptococcus pneumoniae and Pseudomonas aeruginosa. Moreover, infection with a single pathogen, mixed infection of S. pneumonia, and influenza virus have also recently attracted attention. Rapid diagnoses based on gene detection and antigen detection are actively studied, and many of these methods have already been used in clinical settings. The development of new antimicrobial agents for various antimicrobial resistant pathogens is expected, but studies of effective antimicrobial therapies with already available antibiotics have been widely studied previously. Various vaccines have also been studied for the prevention of pneumonia, especially infection with S. pneumoniae.