Résumé : 311 Ubangi infants were studied from birth until 3 yr of age. At birth, serum thiocyanate (SCN) was 3X that of Belgian controls. SCN decreased to normal during the 1st 6 months of life, but then increased again between 1 and 3 yr of age, corresponding to the time of weaning. Increased SCN concn. were associated with increased goitre incidence, decreased serum thyroxine content and increased serum thyrotrophin content.