Abstract: Objective To investigate the effect of riboflavin on mucousmembrane of esophagus,so as to provide evidence for the generalization of the riboflav in-fortifiedsalt.Methods Residents in 21 villages in Cixian,a high incidence area of esophageal cancer in Hebei province were selected and divided into test group using riboflav in-fortified salt and control group using normal salt.From the two groups 275 people randomly selected were tested for the effect of riboflavin with the measurement of erythrocyte glutathione reductase activity coefficient(EGRAC).1 036 residents at 40 to 69 years old got examination of fiberoptic gastroscope with iodine dye staining for evidence of pathological changes in biopsy.The correlation between esophageal cancer and riboflavin level was determined with nested case-control study.Results The mean values general EGRAC of test and control groups were 1.l452 and 1.606,respectively(P<0.01).The results of gastroscope suggested the status of esophags mucosa of study group was better than control gro up(P<0.01).There were a significant correlation between esophageal cancer and family history of tumor(OR=20.94,95%CI=1.37-321.28),and a correlation between esophageal cancer and the lack of riboflavin(OR=15.51,95%CI=1.54-156.08).Conclusion The study indicates that it is practical to improve the nutrition status of riboflav in with riboflavin-fortified salt.Lack of riboflavin might increase the incidence of esophageal cancer.