A Total of 498 cases of hemophilia which were reported by sixteen medical centers in Korea were reviewed and analyzed. Hemophilia A comprised 425 cases (85.3%) and the remaining 73 cases (14.7%) were hemophilia B. One case was female and all other cases were male. There were known hemophilia patients in the family in 43.0% of cases and the involved members were brothers, maternal cousins, maternal uncles, and maternal grandfathers in descending order of frequency. The major symptoms of the patients were hemorrhagic, such as easy bruising and hemarthrosis followed by prolonged bleeding after trauma and soft tissue hematoma. The incidence of hemarthrosis increased significantly with age. The pediatric age group below the age of 15 consisted of 67.1% of the cases. According to the age at diagnosis, half (54.2%) of the severe cases were diagnosed before the age of 1 year. APTT was prolonged over 40 seconds in all cases and 291 cases showed severe prolongation over 80 seconds. Of 498 cases 273 cases (54.8%) belonged to the severe form (factor VII or IX level, less then 1%), whereas 182 cases (36.5%) and 43 cases (8.7%) belonged to the moderate (factor VIII or IX, 2-5%) and mild form (factor VIII or IX, 6-25%), respectively, Chronic arthropathy was present in 236 cases (49.6%), and the incidence increased significantly with age. The management of chronic arthropathy most commonly employed was rehabilitation in 25.4% of cases, but in 50.8% no management was given at all. The involved joints in descending order of frequency were knees, elbows and ankles. The complications were intracranial hemorrhage, Gl bleeding and nerve palsy in 48, 24, and 13 cases, respectively.