Consumption of tomato products is linked to beneficial outcomes through antioxidant and anti-inflammatory mechanisms. The aim of this study was to determine whether a 14-day period of tomato paste supplementation would improve endothelial function. Nineteen volunteers (mean age, 39 ± 13 years; 8 men/11 women) were studied in a randomized (exposure sequence), single-blind (operator), crossover design. The study consisted of a supplementation arm (70 g tomato paste containing 33.3 mg of lycopene) and a control arm, during which no tomato paste was added to their regular diet. Volunteers maintained their regular diet during study arms. Two-week washout periods preceded each arm. Flow-mediated dilatation (FMD) measured by brachial artery ultrasonography was used as an estimate of endothelial function at day 1 (acute response) and day 15 (midterm response). Plasma lipid peroxides were measured with a photometric enzyme-linked immunosorbent assay as an index of total oxidative status. Tomato supplementation led to an overall FMD increase compared with the control period (P = .047 for repeated-measures 3 × 2 analysis of variance). At day 1, FMD was not significantly increased (P = .329). By day 15, tomato supplementation resulted in an increase in FMD by 3.3% ± 1.4%, whereas at the control arm, FMD declined by -0.5% ± 0.6% (P = .03); magnitudes of change are absolute FMD values. Total oxidative status decreased at the end of the supplementation period compared with baseline values (P = .038). Daily tomato paste consumption exerts a beneficial midterm but not short-term effect on endothelial function. Further studies are warranted to explore the effects of tomato paste on endothelial dilation in different age groups and comorbidities.