THE STEVENS-JOHNSON syndrome (erythema multiforme exudativum; Behçet syndrome)1 appears to be causally related to the use of the long-acting sulfonamides as well as other drugs and certain disease conditions.2,3 In an attempt to clarify this association and to delineate the scope of the problem, the Bureau of Medicine of the Food and Drug Administration has surveyed reports from the medical literature, reviewed adverse drug reaction data from other sources in the files of the FDA, and consulted various experts in the field. This communication is a summary of the data obtained and outlines FDA actions on the long-acting sulfonamides. Background Considerations The first long-acting sulfonamide was introduced to American medicine in 1957. At the present time, sulfamethoxypyridazine and sulfadimethoxine are in wide clinical use. These drugs require as little as one oral dose every 24 hours to maintain adequate therapeutic levels, thus differing markedly from the short-acting congeners.