Massive thrombosis or bleeding, hereditary angioedema, Alzheimer's disease, diabetic angiopathy and tumor invasion are some of the human diseases associated with serpins. In addition, mutations that alter serpin conformations (the serpinopathies) lead to lung disease, cirrhosis and a form of familial dementia. The goal of this text is to present the current knowledge on the molecular and cellular basis of serpins and their diseases.