This study was attempted to know the recent changes of the patterns of diseases among Korean children living inurban and rural areas. 21,498 sick-children, who admitted to the thirteen general hospitals which located in urban and rural areas during past five years from Jan. 1994 to Dec. 1978, were analysed for this purpose. 13,759 sick-children(64.0%) were male, others were female and the ratio of sex was 1,8 : 1. 13,210 sick-children(61.4%)wers lived in large cities(over 500,000 population), 23.9% and 14.7$ of total sick-shildren were lived in small and medium sized cities(50,000~500,000 population) and rural areas respectively. There was a tendency to increase year by year in total number of sick children who admitted to the hospitals with the various kinds of diseases. The seasonal incidence of diseases was highest in summer, 27.9% of sick-children were admitted during summer season and the next season was fall. According to the classification of dieases in childhood (by WHO), the main diseases of sick-childen admitted at thirteen hopitals in this study were classified as respiratory tract diseases(6,044 cases, 28.1%), infection and parasitic diseases(5,605 cases, 26.1%) and neonatal disease(4,013 cases, 18.1%). Thr major ten leading causes of admission were as follows; pneumonia(13.6%), diarrheas(12.4%), prematurity(8.6%), neonatal jaundice(8.2%), URI(5.2%), bronchiolitis(3.6%), nephritis(3.3%), bacterial meningitis(3.1%), viral hepatitis(2,8%), pleurisy and empyema(2.4%). The characteristic patterns of diseases in each different resident areas were noted as follows; In large city the incidence of diseases such as intussusception, typhoid fever and hyperbilirubinemia were high comparing to other areas unexpectively. The occurrence of Japanese B encephalitis, tetanus neonatorum, poliomyelitis, septicemia, meningitis and tuberculosis were come into notice in rural areas. Diarrheal disease, prematurity, pyelonephritis and pertussis were still common in small and medium sized cities. The leading diseases in each age groups were; in neonatal period, prematurity(34.9%), hyperbilirubinemia(32.9%) and pneumonia(8.0%); in infancy, diarrheal diseases(28.2%), pneumonia(19.6%) and bronchiolitis(12.5%); in preschool period, pneumonia(16.2%), diarrheas(13.4%) and URI(6.8%); in school period, glomerulonephrithis(11.0%), pneumonia(9.7%) and viral hepatitis(8.1%); in adolescence, glomerulonephritis(11.5%), viral hepatitis(10.5%) and pneumonia(7.6%).