Background-Randomized clinical trials have shown that chocolate intake reduces systolic and diastolic blood pressure, and observational studies have found an inverse association between chocolate intake and cardiovascular disease. The aim of this study was to investigate the association between chocolate intake and incidence of heart failure (HF). Methods and Results-We conducted a prospective cohort study of 31 823 women aged 48 to 83 years without baseline diabetes or a history of HF or myocardial infarction who were participants in the Swedish Mammography Cohort. In addition to answering health and lifestyle questions, participants completed a food-frequency questionnaire. Women were followed from January 1, 1998, through December 31, 2006, for HF hospitalization or death through the Swedish inpatient and cause-of-death registers. Over 9 years of follow-up, 419 women were hospitalized for incident HF (n=379) or died of HF (n=40). Compared with no regular chocolate intake, the multivariable-adjusted rate ratio of HF was 0.74 (95% CI, 0.58 to 0.95) for women consuming 1 to 3 servings of chocolate per month, 0.68 (95% CI, 0.50 to 0.93) for those consuming 1 to 2 servings per week, 1.09 (95% CI, 0.74 to 1.62) for those consuming 3 to 6 servings per week, and 1.23 (95% CI, 0.73 to 2.08) for those consuming ≥1 servings per day (P=0.0005 for quadratic trend). Conclusions-In this population, moderate habitual chocolate intake was associated with a lower rate of HF hospitalization or death, but the protective association was not observed with intake of ≥ 1 servings per day. © 2010 American Heart Association, Inc.