Plasma total homocysteine (tHcy) is a risk factor for cardiovascular disease, adverse pregnancy outcomes and impaired cognitive function. No population-based studies on the possible influence of prandial status on tHcy have been published. The aim of this study was to investigate the variation in plasma tHcy levels in relation to time since last meal. A cross-sectional, population-based study including 18,044 individuals in Western Norway was conducted. Most subjects were in the age groups 40-42 and 65-67 y. Participants who had not eaten during the past 6 h before the blood sampling had significantly higher mean tHcy levels compared with those who had eaten; 11.7 [95% confidence interval (CI): 11.4-12.1] vs. 11.2 (95% CI: 11.1-11.3) micromol/L among men (P = 0.03) and 10.2 (95% CI: 9.9-10.6) vs. 9.7 (95% CI: 9.6-9.7) micromol/L among women (P = 0.003). In all groups except older women, tHcy concentrations were generally higher with increasing time after a meal (P-trend <0.01 in all 3 groups). These findings suggest that fasting status and time since last meal may influence levels of tHcy and should be considered in studies of tHcy as a risk factor for cardiovascular and other diseases, and when comparing tHcy values among studies.