Thyroid nodules are a common clinical problem. Epidemiologic studies have shown the prevalence of palpable thyroid nodules to be approximately 5% in women and 1% in men living in iodine-sufficient parts of the world and up to 30% in iodine deficient regions, such as Germany. The clinical importance of thyroid nodules rests with the need to exclude thyroid cancer which occurs in 5-15%. Differentiated thyroid cancer (DTC), which includes papillary and follicular cancer, comprises the vast majority (90%) of all thyroid cancers. In Germany, approximately 7,000 new cases will be diagnosed in 2011. The yearly incidence has increased from 3.6 per 100,000 in 1973 to 8.7 per 100,000 in 2002, and this trend appears to be continuing. Recurrence-free survival is generally excellent and depends on the risk group.