Cytokines are molecules that influence activation, growth, and differentiation of several target cells. They are proinflammatory mediators, regulate the systemic inflammatory response, playing a crucial role in autoimmune thyroid diseases, and modulate development and growth of both normal and neoplastic thyroid cells. In addition cytokines, as well as chemokines, have been shown to generate antitumor response. In patients with thyroid cancer, cytokines are useful as serum biomarkers, and should be a part of multi-analyte assay in the clinical evaluation of patients with indeterminate fine-needle aspiration cytology. Finally, several cytokines, such as interleukin-6 (IL-6), leukemia inhibiting factor (LIF), and thyroid transcription factor-1 (TTF-1) are expressed in thyroid cancer cell lines, and they can be used for evaluating the inhibitory effects of several drugs in redifferentiation therapies. This review reports the latest advances in defining the actions of cytokines, and resumes the relationship between cytokines, thyroid diseases and thyroid cancer.