Contrary to what would be expected, smoking habits of asthmatics do not differ from those of the general population: approximately 30% of asthmatic patients smoke cigarettes. Although the relationship between smoking and the incidence of asthma has been well explored, little attention has been paid to documenting the relationship between smoking and asthma symptoms among adults with asthma. The objective of this study was to assess the association of cigarette smoking with asthma symptom severity. The present report is of a cross-sectional study of 225 asthmatics, aged 20-54 years, from six general practice clinics in East Anglia, U.K. The outcome measures are overall asthma symptom score (range 6.3-28) and three asthma symptom domains: respiratory (range 1.3-8), daily activity interference (range 2-8), and physical activity interference (range 3-12), generated from the sum of ordinal responses to questions on asthma symptom severity. Of the sample, 27.0% were current and 22.1% were former smokers. Current smokers more frequently had bothersome asthma symptoms than nonsmokers in both unadjusted analyses and analyses controlling for age, gender, recent visits to the general practitioner for asthma, and asthma medication use (p = 0.06). Respiratory symptoms (p = 0.03) and symptoms that affect daily activities (p = 0.03) were more strongly associated with smoking than symptoms that affect physical activities (p = 0.62). Our data suggest that smoking hastens asthma progression or affects disease control. Increased frequency of symptoms may be an indicator for potential morbidity among asthmatics, especially those who smoke cigarettes. The hazards associated with smoking among asthmatics need to be more clearly emphasized by physicians and public health officials in order to convince people with asthma who smoke to stop.