Crohn's disease (CD) is frequently complicated by various nutritional disturbances. Although it is important to correct these disturbances, the nutritional status of CD patients has been poorly documented, especially concerning vitamin status. The aims of this study were (a) to measure the serum concentrations of vitamin A and six other carotenoids (lutein, zeaxanthin, alpha-, beta-carotene, alpha-, beta-cryptoxanthin) in patients with CD and to compare them with those in healthy controls and (b) to follow the changes of serum carotenoid levels in CD patients during treatment. Twenty-eight patients with CD and 23 healthy persons were included in this study. The results of twelve patients were followed up through one year. The patients were free of any nutritional treatment. The serum concentrations of carotenoids were measured with high-pressure liquid chromatography (HPLC). The serum concentrations of five carotenoids were significantly lower in the patients than in the controls (vitamin A, zeaxanthin: P < 0.001; alpha-, beta-carotene: P < 0.01; lutein: P < 0.05). The carotenoid status of the followed patients advanced to the normal range, but this increase was not significant. These findings suggest that there is a deficiency of vitamin A and its provitamins in Crohn' s disease prior to treatment. However, because we did not evaluate the vitamin intake in this study, we could not conclude which of the factors--poor intake, increased requirement, or malabsorption--was more important in decreasing of carotenoid levels.