Objective: Describe secular trends in overall diet quality for coronary heart disease (CHD) prevention during the past two decades (1980-1982 through 2000-2002). Design: Dietary data were drawn from the Minnesota Heart Survey, a repeated population-based survey designed to examine trends in mortality, morbidity, and risk factors for CHD within geographically defined independent probability samples. Subjects/setting: Adults residing in the Minneapolis/St Paul, MN, metropolitan area. Main Outcomes Measures: Dietary intake was assessed by an interviewer administered 24-hour dietary recall from a subsample of survey participants. A Heart Disease Prevention Eating Index was developed to measure overall diet quality by compliance with the current American Heart Association Dietary Guidelines. Statistical Analyses: A generalized linear mixed model was used to examine trends in Heart Disease Prevention Eating Index scores and trends in each element of the index. Results: Age-adjusted mean Heart Disease Prevention Eating Index scores increased in both sexes during the past 2 decades, particularly driven by improvements in total grain, whole grain, total fat, saturated fatty acids, trans-fatty acids, and cholesterol intake. Energy balance, sodium intake, and fish intake were observed to change unfavorably or stay at a low compliance level. Conclusions: Of concern is that improvements in mean Heart Disease Prevention Eating Index appear to have plateaued in 1995-1997, with the mean Heart Disease Prevention Eating Index scores similar between the 1995-1997 and 2000-2002 survey periods. Public health programs for CHD prevention may benefit by applying findings from this study in designing interventions to promote further improvements in the diets of American adults.