SummaryUse of a computer‐based postal questionnaire for the detection of hypothyroidism following radioiodine therapy for thyrotoxicosis. L C. Harrison, D. Buckley and F. I. R. Martin,Aust. N.Z. J. Med,1977,7, pp. 27–32.A computer‐processed postal questionnaire was devised to detect hypothyroidism in patients treated previously for thyrotoxicosis with radioiodine. In a study of 232 patients treated with131J. at the Royal Melbourne Hospital between four and ten years previously, the sum of symptomatic answers in the questionnaire was a sensitive discriminator of hypothyroidism, and allowed 80% of euthyroid patients to be excluded from further assessment. Questions concerned with general well‐being and energy, voice and skin changes, showed the highest sensitivity and specificity. The combination of these questions alone was an effective means of identifying hypothyroidism, with a sensitivity and specificity comparable to the more sophisticated technique of discriminant function analysis. Hypothyroidism had an incidence of between 20% and 35% six to eight years after131I. therapy and was related to a smaller initial goitre size for a given dose of131I. This postal questionnaire, in conjunction with a computer‐based automatic recall system, promises to be an efficient and reliable screening tool for the detection of hypothyroidism in the increasing number of patients “at risk” followi