Although autoimmune hypothyroidism has generally been considered to be a disease that mainly develops because of genetic aberrations and for which adjustment of environment would bring about but slight risk modification, this understanding is increasingly appearing to be incorrect. We describe how iodine intake, smoking cessation and alcohol intake are all strong modifiers of risk that, combined, may influence risk by a factor of up to 30. Unfortunately, promotion of an environment leading to substantial lowering of the risk of autoimmune hypothyroidism (i.e. improvement of dietary iodine deficiency, decrease or cessation of smoking, and moderate alcohol intake) is not incorporated within current public health promoting programs. Nevertheless, it is increasingly becoming evident that knowledge of the importance of these factors for disease development is likely to assist in the planning of health promotion programs, while it will surely also be of value in the care of individual patients.