Of 354 pneumoria patients hospitalized between November 1984 and December 1985, 64 had mycoplasmal pneumonia with fever, cough, rales, and injected throats. Fifty-eight percent of them were between 5 and 9 years of age, and peak incidence was between 5 and 6. The mean age of onset was 6.3 years of age. Thirty-five were male, and 29, female. X-rays showed air-space pneumonia in 73.4%, with a preponderance of segmental or lobdr distribution, and hilar lymphadenopathy was frequent in comparsion with other pneumonias. Antibody titers against M. pneumoniae were distributed between 1:40 and 1:5, 120. Of 24 tested for cold agglutinins, 23 (96%) showed titers of 1:64 or higher. Extrapulmonary manifestations were uncommon, but hepatitis, hematuria, skin rash, gastroenteritis, and myopericarditis (one or more) occurred in some cases. In school-ased children with manifestations of "unusual pneumonia" we should test for Mycoplasma pneumoniae, provide adequate therapy, and prevent life-threatening complications.