We present a retrospective analysis of etiologic factors in 54 cases of Stevens-Johnson syndrome (SJS) diagnosed at Johns Hopkins (1966 to 1976). Our previous study, completed there in 1965, served as a model and data base for comparison. Analysis of the clinical presentation and epidemiologic data in this study reveals no major changes since the earlier series. Although difficult, a decision about cause was made in 82% of the cases. The remainder were considered idiopathic. Drugs and infections are especially suspect as etiologic agents in SJS, but we found no evidence to support one over another. Allergic predisposition, noted in 31% of our cases, may have played a role in the development of SJS. Indeed, the Stevens-Johnson syndrome may have an allergic basis with drugs and infectious agents as sensitizing antigens.