Pertussis was a major cause of morbidity and mortality among infants and children in the United States during the prevaccine era (i.e., before the mid-1940s). Since pertussis became a nationally reportable disease in 1922, the highest number of pertussis cases (approximately 260,000) was reported in 1934; the highest number of pertussis-related deaths (approximately 9000) occurred in 1923. Following the licensure of whole-cell pertussis vaccine combined with diphtheria and tetanus toxoids (DTP) in 1949 and the widespread use of DTP among infants and children, the incidence of reported pertussis declined to a historical low of 1010 cases in 1976 (Figure 1). However, since the early 1980s, reported pertussis incidence has increased cyclically with peaks occurring in 1983, 1986, 1990, and 1993 (1-3). This report summarizes national surveillance data for pertussis from January 1992 through June 1995 from CDC's National Public Health Surveillance System (NPHSS) and Supplementary Pertussis Surveillance System (SPSS) and assesses the effectiveness of pertussis vaccination in the United States during this period using vaccination coverage data from CDC's National Health Interview Survey (NHIS).