PURPOSE: To determine whether CDI can differentiate Graves' disease from other cases of thyroiditis and to determine the relationship between CDI findings and TFT. MATERIALS AND METHODS: Between October, 1995 and January, 1996, 22 cases of diffuse goiter without nodule were prospectively assessed for CDI and TFT. CDI was classified into three groups : Grade 1 (minimal), Grade 2 (moderate), and Grade 3 (marked) ; TFT was also classified into three groups : decreased, normal, and increased thyroid function. The correlation between CDI and TFT was statistically assessed ; each case was diagnosed by aspiration biopsy or clinical laboratory studies. RESULTS: All Graves' disease patients showed good correlation between marked color flows and increased thyroid function. The CDI findings of other cases of thyroiditis showed variable color flow and TFT. We found significant differences between the two disease groups. CONCLUSION: CDI can help differentiate Graves' disease from other cases of thyroiditis and additional assesment using TFT will help in the diagnosis of diffuse goiter. The "thyroidinferno" pattern is not a specific finding of Graves' disease.