The paper presents the importance of cytochemical research in the diagnostics of thyroid gland diseases. It is considered that this research usefully supplements the standard cytodiagnostics of the thyroid, especially in clarifying functional and morphological changes in goiter. Given are the basic principals of cytochemical analyses as well as the valuing, in other words, the quantification of cytochemical results. The following methods are more closely described: PAS, alpha-naphthilacetate esterase, naphthol AS-D acetate esterase, peroxidase, beta-glucuronidase and alkaline phosphatase.