A study was conducted in 12 free-living subjects to determine quantitative and qualitative plasma phospholipid (PL), free fatty acid (FFA), triglyceride (TG), and cholesterol ester (CE) fatty acid (FA) variations over time (0.8, and 22 mo) and to correlate these FAs with dietary intake. Diet, reported by use of a food frequency questionnaire (FFQ), did not change over time. Most FA variations were quantitative, occurring in FFA and CE fractions. Correlations between diet and FAs occurred mostly in men for whom dietary percent fat energy was positively correlated with percent monounsaturated plasma TG FAs, and ethanol (g/d) was positively correlated with plasma CE 16:1 omega 7 (mumol/L). These findings indicate that quantitative variations exist in plasma FAs of a normal population, with no detectable alteration in diet; the FFQ may be used to reflect the qualitative status of plasma FA. Factors such as ethanol consumption and sex differences may influence FA metabolism.