A summary of various data of the thyroid function test and clinical and pathological findings over 94 patients who have appreciable filling defect on their thyroid scan, among 860 patients received thyroid function tests due to susppected thyroid diseases at the Radiology and Nuclear Medicine, College of Medicine, Yonsei University, was discussed and evaluated. 1. The incidence of cold nodule in female is about 9.5 times more frequent than in male, and the majority of patients (72.3%) were in the 2nd through 3rd decades. 2. The cold nodules are more distributed in right lobe(60.0%) than in left lobe and more distributed in lower portions of both lobes (54.2%) than in middle and upper portions. 3. The clinical symptoms supporting the evaluation of thyroid functional state in various thyroid diseases are not helpful for patients with cold nodules. 4. Considering the mean values of various thyroid function tests of patients with cold nodules, the value of 1-131 thyroid uptake tes is in lower limit of normal range, the value of T3-RBC uptake test in normal range, and the value of PBI test in upper limit of normal range. 5. Considering the filling defect portion on thyroid scan by cold nodule as fraction, in the case of involving entire one lobe the values of all thyroid function test are more meaningfully decreased than in other cases but the case of involving more than half an lobe to one lobe compared with the case of involving less than half a lobe, the values of thyroid uptake tests are not meaningfully changed but the values of T3-RBC uptake tests or PBI tests are moreover increased in the former.