The present paper provides a more detailed review of some themes already discussed in previous papers concerning the changing face of pneumonia in an area of the central Adriatic coast of Italy, including an ex novo examination of the correlations between radiological findings and serological groups not previously reported. The discussion concentrates particularly on some questions raised by the research, such as the apparent rarity of pneumococcus, the elevated number of seronegatives appearing as atypical pneumonia, the high percentage of "bacterial-type" cases occurring among the viral-like, and the therapeutic problem.