Mycoplasma pneumonia has known to be a not uncommon disease. However, the differential diagnosis of mycoplasm pneumonia with other viral pneumonia is difficult because of its variable clinical symptoms and atypical radiologic findings. A retrospective review was made of plain chest radiologic findings and clinical manifestations of 33 patients, who were admitted at Yonsei University Hospital from January, 1985 to February, 1990. The most prevalent age was 4th decade(33%) and main symptoms were cough(24/33), fever(2/33) and sputum (20/22). The most frequent season was winter(50%). The radiologic patterns were predominently interstitial(15/33), combined(13/33) and predominently alveolar (5/33) lesion. In alveolar infiltrations cases(n=18), unilateral single lobe involvement was the most common(17/18) and left lobe(8/18) was predominently involved. Associated radiologic findings were hilar lymphadenophthy (4/33), pleural effusion (4/33) and cardiomegaly(7/33).