Asthma is a chronic illness that has been increasing in prevalence in the United States since 1980. In 2000, asthma accounted for 4,487 deaths, approximately 465,000 hospitalizations, an estimated 1.8 million emergency department (ED) visits, and approximately 10.4 million physician office visits among persons of all ages. To provide prevalence data for state and local health department asthma programs, the Behavioral Risk Factor Surveillance System (BRFSS) collects data each year from the 50 states, the District of Columbia, and three U.S. territories. This report summarizes asthma prevalence data for adults collected from the 2001 BRFSS survey and from the eight states that used the adult asthma history module. Findings from BRFSS indicate that approximately 7.2% of U.S. adults have current asthma. ED visits for asthma varied more than any other characteristic among the eight states that used the adult asthma history module. In Mississippi, 67.3% of respondents with current asthma reported no ED visits during the preceding 12 months, compared with 87.6% in Washington state. Continued use of the BRFSS asthma prevalence questions and the asthma history module will allow state health departments to monitor trends in asthma prevalence and control and to direct public health asthma interventions.