In Norway, epidermolysis bullosa (EB) has been studied from the clinical, genetic and epidemiologic viewpoints. Heterogeneity is found both in the EB simplex (EBS) and the EB dystrophica (EBD) group. One new EBS and two new EBD varieties were found in addition to previously known types. At least five nonidentical recessive EBD genes could be defined and suggestive evidence for allelism between some of them were found. A classification of hereditary EB is presented.