The diagnostic value of cytological, serological and scintigraphical examination was evaluated in 20 histologically verified cases of thyroid disorder. The predictive values of specificity as to malignancy, thyroiditis and thyroid autoantibodies were respectively 0 percent (0-71), 80 percent (28-99) and 75 percent (19-99), and the predictive values of sensitivity were 88 percent (64-99), 100 percent (78-100) and 94 percent (70-100). Cold nodules were malignant in 40 percent. Fine needle biopsy can be used as a supplementary test without any risks and is a valuable aid in the diagnosis of Hashimoto's thyroiditis, but not in the diagnosis of malignant lesions. If any clinical or scintigraphical (cold nodule) suspicion of malignancy exists, a surgical biopsy must be done.