Background: Most studies of Mycoplasma pneumonia involve a group of admitted patients in hospital, usually with major medical illness. So we investigated the epidemiologic and radiologic features during the course of outbreak of pneumonia in Chunnam coastal area. Methods: We retrospectively studied the epidemiologic and clinical feature of 105 patients with serologically proven Mycoplasma pneumonia treated at Kwang-Yang Hospital during a epidemic period of Jun.1993 to Dec.1993. All cases of pneumonia developed in this period were also reviewed and compared with serologically proven group. Results: 1) There were 63 males and 42 females. 2) More than half(57%) of cases belonged to 5-9 years of age group, and mean age was 6.5 years old. Mean age was steadily decreased as prevalence of Mycoplasma pneumonia had been subsided. 3) A major determinant of the outbreak seemed to be the population density rather than the population size. 4) The common radiologic features were interstitial in type, and 67 cases was restricted to one lobe. Lobar types are more common in late childhood, and interstitial or diffuse types in early childhood. Conclusion: These epidemiologic and radiographic characteristics would contribute to the diagnosis of Mycoplasma pneumonia.