256 patients were referred to the endocrinic clinic because of enlarged thyroid gland. All of them except one were subjected to thyroid scintigraphy (TS). The scintiscans were cold in 123 patients. The cold scintiscans were distributed evenly on the various referral diagnoses with half the patients of each group having cold TS. A total of 216 of the referred patients underwent surgery, among them the 123 with cold TS. If the solitary adenomas are left out of account, there was poor agreement between referral diagnosis, primary tentative hospital diagnosis, and surgical findings. Five patients were found to have thyroid cancer (TC), none of whom had been referred with this diagnosis. For the entire material the incidence of TC was 2.3% (95% confidence limits: 0.8--5.7%). Calculated on the basis of those patients who had cold TS, the incidence was 2.4% (95% confidence limits: 0.8--7.1%). It is concluded that the diagnosis of TC is difficult to establish preoperatively, and that TS is of no greater diagnostic value in this connection.