This study was undertaken to discover whether reduced levels of micronutrients in patients with sickle cell disease are due to the generalized undernutrition. Protein undernutrition was determined by measuring plasma levels of prealbumin. One micronutrient, carotene, was also simultaneously assayed in the plasma. Eighteen sickle cell disease patients were enrolled at random. Controls were 19 normal volunteers and seven family members of the patients. The patients showed significantly reduced levels of prealbumin and carotenoids compared with either normals or family members. Levels of carotenoids did not significantly correlate with level of prealbumin, which suggests that the undernutrition was not the only factor contributing to lower levels of carotenoids in these patients.