Although a number of epidemiological studies have evaluated the association between ss-carotene and the risk of cardiovascular diseases, there has been little research on the role of lycopene, an acyclic form of ss-carotene, with regard to the risk of cardiovascular disease. We investigated the relationship between plasma concentrations of lycopene and intima-media thickness of the common carotid artery wall (CCA-IMT) in 520 middle-aged men and women (aged 45 to 69 years) in eastern Finland. They were examined from 1994 to 1995 at the baseline of the Antioxidant Supplementation in Atherosclerosis Prevention (ASAP) study, a randomized trial concerning the effect of vitamin E and C supplementation on atherosclerotic progression. The subjects were classified into 2 categories according to the median concentration of plasma lycopene (0.12 micromol/L in men and 0.15 micromol/L in women). Mean CCA-IMT of the right and left common carotid arteries was 1.18 mm in men and 0.95 mm in women with plasma lycopene levels lower than the median and 0.97 mm in men (P:<0.001 for difference) and 0.89 mm in women (P:=0.027 for difference) with higher levels of plasma lycopene. In ANCOVA adjusting for cardiovascular risk factors and intake of nutrients, in men, low levels of plasma lycopene were associated with a 17.8% increment in CCA-IMT (P:=0.003 for difference). In women, the difference did not remain significant after the adjustments. We conclude that low plasma lycopene concentrations are associated with early atherosclerosis, manifested as increased CCA-IMT, in middle-aged men living in eastern Finland.