Thyroid iodine concentration and total thyroid iodine were determined by an automated technique by means of the ceric arsenious acid reaction in 42 males and 13 females. The thyroids were taken from autopsy material in a region with a low dietary intake. The accuracy of the method to estimate iodine was checked by neutron activation analysis. There was an excellent correlation between the iodine contents of thyroid specimens, when measured by chemical or by activation analysis. The mean iodine concentration was 1.86 mg/g dry weight and was found to be lower than in non-goitrous regions. In goitres, the mean iodine concentration was significantly lower, and the mean total thyroid of normal weight. There was no significant difference in iodine concentration and total iodine between males and females. The thyroid iodine concentration did not depend upon age in adults. The data were log normally distributed. It was established that mean iodine concentrations under 2 mg/g dry weight or 0.45 mg/g fresh weight are to be regarded as an important index of iodine deficiency.