Technical Abstract: Self-perceived lactose intolerance may result in adverse dietary modifications; thus, more studies are needed to understand the prevalence of self-perceived lactose intolerance and how it relates to calcium intake and selected health conditions. The objective was to examine the effects of self-perceived lactose intolerance as it relates to calcium intake and specific health problems that have been attributed to reduced intakes of calcium and dairy foods in a nationally representative multiethnic sample of adults. This was a cross-sectional study in a national sample of 3452 adults. The relation between self-perceived lactose intolerance, calcium intakes, and physician-diagnosed health conditions was analyzed by using linear regression analyses. Of the total sample, 12.3% of respondents perceived themselves to be lactose intolerant. The age-adjusted prevalence of self-perceived lactose intolerance was 7.8% for non-Hispanic whites, 20.1% for non-Hispanic blacks, and 8.8% for Hispanics. Respondents with self-perceived lactose intolerance had significantly lower (P less than 0.05) average daily calcium intakes from dairy foods than did those without self-perceived lactose intolerance. A significantly higher (P less than 0.05) percentage of respondents with self-perceived lactose intolerance than of respondents without self-perceived lactose intolerance reported having physician-diagnosed diabetes and hypertension. The odds of self-reported physician-diagnosed diabetes or hypertension decreased by factors of 0.70 and 0.60, respectively, for a 1000-mg increase in calcium intake from dairy foods per day. In conclusion, self-perceived lactose-intolerant respondents had a significantly lower calcium intake from dairy foods and reported having a significantly higher rate of physician-diagnosed diabetes and hypertension.