In a prospective study, Chlamydia pneumoniae was identified as the etiological agent in 62 (17.9%) of 346 adult patients hospitalized over the course of one year for community-acquired pneumonia at the Soroka Medical Center in Beer-Sheva, Israel. The diagnosis of C. pneumoniae infection was based on serological testing of antibodies by the MIF technique. In 43 of these patients (69.4%), at least one other etiological agent, in addition to C. pneumoniae for community-acquired pneumonia was identified. Streptococcus pneumoniae was identified in 34 patients with C. pneumoniae (54.8%), as an additional causative factor in infection. Community-acquired pneumonia patients with C. pneumoniae were significantly older than non-C. pneumoniae patients (p = 0.03), had a higher APACHE II score on admission (p < 0.05), a higher rate of positive blood cultures (p = 0.02), and longer periods of hospitalization (p = 0.022). Seven patients with pure C. pneumoniae infection recovered, despite treatment which is not considered to be specific for C. pneumoniae. It was concluded that C. pneumoniae is a common etiological agent for community-acquired pneumonia in our region, particularly in the elderly, and is characterized by a high rate of concomitant infections with other pulmonary pathogens. No specific clinical or radiological pattern was discerned that could distinguish between C. pneumoniae community-acquired pneumonia and non-C. pneumoniae community-acquired pneumonia.