The present work reports the findings of a ten-year, research, the aim of which is to outline current views of pneumonia in a zone of the Middle Adriatic (USL 17-Regione Marche). The study confirmed, in its entirety, a lesser aggressiveness and loss of the "seasonal feature" of today's pneumonias. The high incidence of Atypical Pneumonia (AP) due to viral-like microorganisms (mycoplasma, chlamydia, coxiella, legionella) and an even higher one of unknown etiology is reported. After having analysed the most likely reasons for such a change and its various implications, the authors conclude that this type of research should be extended in order to trace a map of the more common infectious agents in single geographical zones, as an indispensable premise for a more concrete etiological diagnosis and for a more rational choice of the antibiotic.