BACKGROUND AND OBJECTIVES: Congestive heart failure is one of the most frequent problems in cardiovascular patients. However, very little data concerning this syndrome in Korea was available. The objectives of this study were to evaluate the demographic and clinical characteristics of hospitalized Korean patients with congestive heart failure. SUBJECTS AND METHODS: Six university hospitals that fulfilled the protocol for clinical information of the patients with heart failure, were prospectively engaged in this study. Six hundred and ninety patients, admitted between Jan. 1. 1998 and Dec. 31. 1999, were enrolled. RESULTS: Ischemic heart disease was the most frequent underlying disease (33.2%), with the other causes of heart failure being cardiomyopathy (23%), hypertensive heart disease (22%) and valvular heart disease (12.7%). Compared with ischemic cardiomyopathy, the patients with idiopathic dilated cardiomyopathy were younger (61.1+/-16.6 vs. 66.9+/-10.3, p<0.05), had less incidence of diabetes (16.8% vs. 32.2%) and smoked less (13.5+/-21.5 vs. 20.4+/-26.0 pack-year). The common aggravating factors were arrhythmia (22%), myocardial ischemia (21.7%) and infection (18.7%). Thirty nine (5.7%) patients died during the one year follow up period. Ischemic heart disease was the main underlying disease in the fatal cases (46.2%). CONCLUSION: Ischemic heart disease was the major cause of heart failure, and the leading cause of death in Korean patients with congestive heart failure.