To assess approaches to the diagnosis and therapy of patients with nontoxic multinodular goiter, a questionnaire was circulated to all members of the American Thyroid Association (ATA). An index case report was presented (42-yr-old woman with an irregular, nontender, bilaterally enlarged thyroid of 50-80 g and no clinical suspicion of malignancy or thyroid dysfunction), and 11 variations were proposed to evaluate how each alteration would affect management. One hundred and forty responses were retained (approximately 50% of clinically active ATA members). For the index case, a TSH determination was the routine choice of 100%, and serum thyroid autoantibodies were measured by 74%. Simultaneous use of serum TSH, a thyroid hormone assay, and antithyroid peroxidase was employed by 49%. Only 4% included a calcitonin assay. The median number of blood tests ordered was 3 (range, 1-7). Ultrasound was used by 59%, thyroid scintigraphy by 24%, and both imaging modalities by 11%. Fine needle aspiration biopsy (FNAB) was performed by 74%. If scintigraphy showed inhomogeneous tracer distribution or a dominant hypofunctioning region, FNAB was performed by 15% and 97%, respectively. L-T4 treatment was preferred by 56%, radioiodine by 1%, surgery by 6%, and 36% would recommend no treatment. A large goiter, a history of external radiation, or rapid growth increased the preference for surgery. In case of a suppressed serum TSH level, radioiodine was used by 56%. In conclusion, in the work-up of patients with nontoxic multinodular goiter, ATA clinicians employ determinations of TSH often combined with a T4 and/or T3 assay and antithyroid peroxidase antibodies. Thyroid imaging, primarily ultrasound, is performed by more than two thirds, and FNAB by three fourths. This diagnostic evaluation is significantly less extensive than that of the European Thyroid Association members, but the distribution of treatment choices is quite similar. In accordance with their European colleagues, the majority of ATA members prefer the use of L-T4 therapy. There is, however, still a wide variation in the perceived optimal management of this condition among members of both organizations.