Commonly the Endocrine Orbitopathy (EO) is associated with Graves' disease, but encountered also with Thyroiditis Hashimoto and hypothyroidism. The EO may coincide, precede, or appear during the endocrine dysfunction. EO and thyroid dysfunction are due to an autoimmune process caused by specific immunoglobulins G (IgG). Such IgG behave like TSH, inducing hyperthyroidism, and/or may be goitrogen or cytotoxic to thyroid cells as well as to orbital tissue. For the treatment outcome of EO an optimal hormonal thyroid status is mandatory, and a progressing malignant EO requires early, and high dose steroid treatment.