Dietary intake of tomatoes and tomato products containing lycopene, an antioxidant carotenoid, has been shown in recent studies to reduce the risk of cancer. This study was conducted to investigate the serum and prostate tissue lycopene and other major carotenoid concentrations in cancer patients and their controls. Serum lipid and protein oxidation was also measured. Twelve prostate cancer patients and 12 age-matched subjects were used in the study. Significantly lower serum and tissue lycopene levels (44%, p = 0.04; 78%, p = 0.050, respectively) were observed in the cancer patients than in their controls. Serum and tissue beta-carotene and other major carotenoids did not differ between the two groups (p = 0.395 and p = 0.280, respectively). Although there was no difference (p = 0.760) in serum lipid peroxidation between cancer patients and their controls (7.09 +/- 0.74 and 6.81 +/- 0.56 mumol/l, respectively), serum protein thiol levels were significantly lower among the cancer patients (p = 0.026). This study demonstrates that the status of lycopene but not other carotenoids in prostate cancer patients is different from controls. The role of dietary lycopene in preventing oxidative damage of biomolecules and thereby reducing the risk of prostate cancer needs to be evaluated in future studies.