This revision of the Immunization Practices Advisory Committee (ACIP) statement on diphtheria, tetanus, and pertussis updates the statement issued in 1985, and incorporates the 1987 supplementary statement, which addressed two issues: a) the risks and benefits of pertussis vaccine for infants and children with family histories of convulsions; and b) antipyretic use in conjunction with diphtheria and tetanus toxoids and pertussis vaccine absorbed (DTP) vaccination among children with personal or family histories of convulsions (1,2). This document presents new recommendations for epidemiologic investigation and management of contacts of diphtheria patients. The updated recommendations include a review of the epidemiology of the three diseases and descriptions of the available immunobiologic preparations with appropriate vaccination schedules. Also included are a) new information on and reassessment of the possible relation between receipt of DTP and the occurrence of serious acute neurologic illness and permanent brain damage, b) revisions in the recommendations on precautions for and contraindications to pertussis vaccine use, and c) revisions on recommendations for chemoprophylaxis for household and other close contacts of pertussis patients. The Committee has reviewed and taken into consideration the recent report by the Institute of Medicine entitled, "Adverse Effects of Pertussis and Rubella Vaccines" in making these recommendations.