Nodular goiters are encountered commonly in clinical practice by primary care physicians, endocrinologists, surgeons, and otolaryngologists. Epidemiologic data suggest that in the United States, the incidence of such goiters is approximately 0.1% to 1.5% per year, translating into 250,000 new nodules annually. Nodular goiters are more common in women than in men, with advancing age, and after exposure to external irradiation. These goiters may be asymptomatic, with normal TSH levels (nontoxic), or may be associated with systemic thyrotoxic symptoms (toxic MNG or Plummer's disease). Diagnostic evaluation of patients with nodular goiters consists of clinical evaluation, biochemical testing, FNA, and imaging studies. The serum TSH level is a sensitive and reliable index of thyroid function. FNA results are pivotal to assess cancer risk in patient management for prominent palpable and suspicious nodules. Chest radiography, high-resolution ultrasonography, and computed tomography help to delineate the size and extent of a goiter in evaluating compression symptoms. Indications for treatment in patients with MNG include hyperthyroidism, local compression symptoms attributed to the goiter, cosmesis, and concern about malignancy based on FNA results. The use of levothyroxine suppression therapy to effectively decrease and control MNG size is controversial. Thyroid hormone should not be used, however, in patients with suppressed serum TSH levels, to avoid the development of toxic symptoms. Management of toxic MNG by surgery is well established. Radioiodine is also effective therapy for many of these patients. When treatment is necessary for nontoxic MNG, surgical excision is preferred. Our recommendations are as follows. For patients who have small, nontoxic multinodular goiters that are clinically asymptomatic, who are biochemically euthyroid according to serum TSH levels, and who have prominent palpable or suspicious nodules benign by FNA, yearly evaluation with serum TSH determinations and thyroid palpation is sufficient. Patients with modest but stable MNG size and normal serum TSH levels may also be managed by yearly clinical observation. In this second group, levothyroxine suppression therapy is often unsuccessful and has the potential for untoward effects from exogenous hyperthyroidism. For large nontoxic multinodular goiters with local compression symptoms, the preferred treatment is surgery. In patients with toxic MNG, treatment with either surgery or radioiodine is recommended, although patients with large goiters and large, autonomously functioning nodules become euthyroid more quickly following surgery.