Esophageal brush cytological screening was undertaken and blood concentrations of micronutrients (vitamin A, E, B12, folic acid and methionine) determined from adults at risk for esophageal carcinoma (EC) in Transkei and Ciskei, Southern Africa. Age-standardised EC rates per 100,000 per annum for both sexes in high, intermediate and low risk districts in Transkei were 74, 51 and 34, respectively. Corresponding rates in high and low EC risk districts in Ciskei were 129 and 9, respectively. Esophageal cytological changes including esophagitis, signs of folic acid deficiency, cellular atypia, dysplasia and cancer, were more prevalent in patients from high than from low EC risk areas. Dietary questionnaires revealed that corn was the main dietary staple in all populations, but that lower intakes of green vegetables, fruits and animal protein occurred in the high risk areas. Significantly lower concentrations of vitamins A, E, B12 and folic acid were present in the blood of patients presenting with cellular dysplasia or malignancy than in cytologically normal patients and in patients from low risk areas. Concentrations of red cell and plasma folate were significantly lower in patients presenting with cytological signs of folic acid deficiency or cellular atypia. The association of vitamin A, vitamin E and folic acid deficiencies with specific esophageal cytological abnormalities in populations at risk for EC is reported for the first time.