Solitary cold thyroid nodules occur in approximately 4% to 7% of adults. The diagnostic workup should be designed to predict the likelihood of malignancy. The presence of risk factors for carcinoma raises the index of suspicion and should prompt consideration of surgical excision of the nodule. An orderly sequence of diagnostic tests should be performed in every patient with a thyroid nodule, and additional special tests may be needed under specified clinical circumstances. With careful selection high risk patients can be referred for neck exploration and low risk patients can be followed without operation.