The previous knowledge related to auto-immune occurrences in thyroid gland disease are described in the review, showing main antigens, auto-antibodies, the inclusion of humoral and cellular immunity in the most frequent thyroid gland diseases. In spite of many learnings, which are broadened every day, the exact sequence of events and roles of external factors in genetically predisposed persons is still unknown. An identification of auto-antibodies gives direct evidence about the auto-immune process, as they are present among the majority of patients with Graves' hyperthyroid and Hashimoto's thyroiditis. Immuno globulins, created by plasma cells, linked with cytokinins from lymphocyte CD4 T, engage the cell auto-immune reaction in these diseases. Being acquainted with all events in the auto-immune process, we can understand better why these frequent diseases occur, why do they have chronic and recidivous course, why they are more frequent with women and within some families, and why they enable us to make a better diagnosis and treatment of these patients.