A high intake of beta-carotene has been associated with a decreased risk for cardiovascular disease. To evaluate whether beta-carotene intake may exert a protective effect through an impact on lipoprotein metabolism, we conducted a randomized, double-blind trial in healthy, male cigarette smokers. Total cholesterol, high-density-lipoprotein (HDL) cholesterol, apolipoprotein A-I (apo) A-I, apo B-100, and lipoprotein(a) were measured before and after 14 wk of treatment with beta-carotene (20 mg/d, n = 25) or placebo (n = 25). The beta-carotene and placebo groups were comparable with respect to all initial characteristics, but initial apo B-100 was significantly higher in the beta-carotene group (1.23 vs 1.44 g/L). During the intervention, plasma concentrations of beta-carotene increased 15-fold in the treatment group. Mean concentrations of total and HDL cholesterol, lipoprotein(a), apo A-I, and apo B-100 did not change significantly in either group. We conclude that a 20 mg beta-carotene supplement/d does not influence plasma lipoproteins in healthy male smokers.