Serum samples from girls from an elementary school in Western Sudan with grades 0,1 and II/IIIgoitre were examined for their thiocyanate, cysteine, thyroxine, TSH and T3 concentrations. The concentrations of thiocyanate in all girls was higher than that reported in the literature for Nigerians, but the concentrations of thiocyanate were nevertheless significantly elevated, and those of thyroxine significantly lowered in girls with grades I and II/IIIgoitre as compared with grade 0. There were no significant differences between any of the groups in the concentrations of cysteine or TSH and T3. The predominant staple food eaten in this area of Sudan is millet and evidence is produced that this contains a goitrogenic thionamide which could be a factor in causing the endemic goitre.