Therapy has improved the survival of heart failure (HF) patients. However, many patients progress to advanced chronic HF (ACHF). We propose a practical clinical definition and describe the characteristics of this condition.Patients that are generally recognised as ACHF often exhibit the following characteristics: 1) severe symptoms (NYHA class III to IV); 2) episodes with clinical signs of fluid retention and/or peripheral hypoperfusion; 3) objective evidence of severe cardiac dysfunction, shown by at least one of the following: left ventricular ejection fraction b 30%, pseudonormal or restrictive mitral inflow pattern at Dopplerechocardiography; high left and/or right ventricular filling pressures; elevated B-type natriuretic peptides; 4) severe impairment of functional capacity demonstrated by either inability to exercise, a 6-minute walk test distance b 300 m or a peak oxygen uptake b 12-14 ml/kg/min; 5) history of N1 HF hospitalisation in the past 6 months; 6) presence of all the previous features despite optimal therapy. This definition identifies a group of patients with compromised quality of life, poor prognosis, and a high risk of clinical events. These patients deserve effective therapeutic options and should be potential targets for future clinical research initiatives.