Radioiodine monitoring in a reactor environment is important in the detection of any unwarranted radioactivity release. Bovine thyroids have been examined for monitoring iodine in various establishments in the U.S. In India, cows' thyroids are not available, whereas goats are slaughtered for meat and the thyroids are freely available. The paper reports the results of a survey to determine preoperational radioiodine content in goat thyroids in the Tarapur Atomic Power Project environment and reports on associated investigations for the use of goat thyroids as indicators for radioiodine. The study showed that the goat thyroid weighs 1.9 ± 0.1 g and the average iodine content is 1 mg/g thyroid. Comparison of the iodine content in the thyroid tissues of goats and cows' milk showed that the thyroid has nearly 20,000 times higher iodine content. Monitoring of thyroids in 1967 did not show any activity in May (premonsoon period), but in August the thyroids showed considerable amounts of 131I probably due to the French weapons test in July. In this period an examination of grass, milk (cow's) and goat thyroids showed that 131I in a gram of thyroid tissue corresponded to that in 8 kg of grass and in 13.5 l. of milk. In January 1968, thyroids again showed radioiodine following the Chinese test in December 1967.