OBJECTIVES: The objective of this study was to quantify, for the first time in a Spanish population, the time and cost burden of informal care for pts with heart failure. METHODS: A descriptive analysis of a multicenter, prospective observational study was performed. Pts who met inclusion criteria were followed-up for 12 months, with 3 visits programmed at baseline, 6 and 12 months. Baseline characteristics and caregiver’s information were registered for every pt. Once identified total hours, the replacement cost method was used. RESULTS: A total of 330 pt were included, 74.2% men, mean age was 62.9 years. 82.4% were in NYHA class II, 16.4% NYHA class III and 1.2% NYHA class IV. A 28.5% needed support for daily living. Ninety four informal caregivers were identified, mean age of 58yo, mostly women (85.1%). Main relationship with caregiver was spouse/couple (77.7%), followed by son/daughter (14.9%). Number of weekly hours of main caregiver was estimated at 44.3 hours (40.6 hours for patients NYHA class II and 53.3 hours for patients NYHA class III-IV) and shadow prices values from 8-13€/hour. Total costs associated to informal caregiving increased between €21,298-€34,609 per pt of which between €18,892-€30,049 are informal costs associated with the main caregivers. Likewise, focusing on main caregivers, using the proxy-good method and the shadow prices shown, the cost of replacing services by care giving a Class II patient (2,115 yearly hours) were between €16,919-€27,494 for pts in NYHA class II; and between €22,230-€36,123 for caregiving a Class III or IV pt (2,779 yearly hours). CONCLUSIONS: Almost a 30% of pts with chronic symptomatic HF in Spain required support from an informal caregiver, which represents a significant burden for society and often has not been accounted for in economic evaluations of treatments for heart failure. Costs for informal care are associated  with disease severity as measured by NYHA class.