The present survey evaluated current trends in the management of the nontoxic solitary thyroid nodule by expert endocrinologists in North America and compared their results with a similar European Thyroid Association survey. A questionnaire was circulated to all clinical members of the American Thyroid Association. An index case (a 42-yr-old woman with a solitary 2 x 3-cm thyroid nodule and no clinical suspicion of malignancy) and 11 variations were provided to evaluate how each alteration would affect management. One hundred and seventy-eight members replied and 142 responses were retained for analysis, corresponding to a response rate of 43% of clinically active members. Based on the index case, basal serum TSH was the routine choice of 99%, and serum T4 and/or free T4 were included by 61% of the respondents. Thyroid peroxidase antibodies and serum calcitonin were included by 30% and 5%, respectively. Thyroid scintigraphy was used by 23% ((123)I, 63%; (99m)Tc, 31%; (131)I, 6%), and ultrasonography was used by 34%. Fine needle aspiration biopsy was routinely used by all and was guided by palpation in 87%. Based on the individually chosen diagnostic tests indicating a benign solitary thyroid nodule in a euthyroid subject, L-T4 treatment was advocated by 47%, no specific treatment and follow-up was advocated by 52%, and surgery was advocated by 1%. Clinical factors suggesting thyroid malignancy (e.g. rapid nodule growth and a large nodule of 5 cm) lead a significant number of clinicians (40 - 50%; P < 0.00001) to disregard biopsy results and to choose a surgical strategy. Nevertheless, North American endocrinologists heavily rely on fine needle aspiration biopsy results. Compared to the European Thyroid Association survey, North American endocrinologists use imaging [scintigraphy, 23% vs. 66% (P < 0.0001); ultrasonography, 34% vs. 80% (P < 0.0001)] and serum calcitonin (5% vs. 43%; P < 0.0001) less frequently. A nonsurgical strategy prevails in North America, and despite controversies on the effect of L-T4, this treatment is supported by more than 40% in both Europe and North America.