Abstract. In order to know how thyroid nodules and differentiated thyroid cancers are investigated and treated in 1988, an international inquiry was performed by mean of a questionnaire based on a well-defined case report of a 35-year-old female with a solitary small thyroid nodule. Clinicians were asked to indicate their diagnostic and therapeutic approaches to the reported case and to some variations. Analysis of the 157 responses from thyroid experts showed that three in vitro tests (sensitive-TSH, free T4 and total T4) and three in vivo tests (99mTc or radioiodide scintiscan, fine needle aspiration and ultrasonography) were performed most frequently. In the case of a solid and cold nodule and in the absence of fine needle aspiration results, 19% of respondents advocated suppressive therapy and 81% surgery. In the same clinical case, but whom fine needle aspiration had been performed and cytology was benign, surgery was advocated by 24%, suppressive therapy by 48% and a regular follow-up without treatment by 28% of respondents. When surgery was performed and the diagnosis was a differentiated thyroid cancer, (near) total thyroidectomy was more frequently chosen than partial thyroidectomy in both papillary (60 and 40%, respectively, of respondents) and follicular (74 and 26%, respectively, of respondents) cancers; 80% of clinicians did not change their surgical technique in relation to histological type of the tumour. Total thyroidectomy was more often recommended in most of the clinical or anatomical variations compared with the basic case report. Pre- or postoperative hormonal therapy was initiated with L-T4 and TSH suppression was controlled by sensitive-TSH and thyroglobulin determinations. After total thyroidectomy, 131I was used with similar modalities for papillary and follicular cancers to ablate a thyroid remnant.