The severe skin reactions erythema exsudativum multiforme majus (EEM with mucosal involvement, EEMM), Stevens-Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN) are difficult to study as they are very rare diseases with an incidence of about two cases per 1 million inhabitants per year. We report on the structure of a registry with the aim of ascertaining all hospitalized cases of EEMM, SJS, and TEN in western Germany and Berlin. The registry is structured as an intensive reporting system, regularly contacting more than 1500 departments including 100% of the burn units (n = 34), departments of pediatrics (n = 241), departments of dermatology (n = 106), and 100% of all internal medicine departments in hospitals with intensive care facilities or with more than 200 beds (n = 1161). With a coverage rate up to 95% based on the number of responding departments between April 1, 1990 and December 31, 1992, from a total of 767 reported cases 353 patients with EEMM, SJS, and TEN were finally included in the registry. Most of these patients were directly reported to the registry; only 2.54% (9 of 353) were primarily registered by the German spontaneous reporting systems. Assuming an average population of 64.5 million for western Germany and Berlin an incidence up to 1.89 per 1 million inhabitants per year could be calculated for SJS and TEN.