Background: ß-Antagonists have recently been proposed for the treatment of chronic asthma; however, concerns regarding risk of acute bronchoconstriction in clinical trials remain. Objective: To determine the frequency of oral ß-blocker prescribing in patients with asthma and associations with severe asthma exacerbations requiring oral steroids in patients with active asthma defined by prior asthma-related medication use. Methods: Patients with asthma registered on 31 March 2007 and all asthma-related medications from the preceding 2 years were identified from anonymised clinical data from one-third of Scottish general practices. The main outcome measure was the relative incidence of active asthma patients receiving oral steroids following a new oral ß-antagonist prescription. Results: Of the 53 994 adult patients identified with asthma 1527 (2.8%; 95% CI 2.69% to 2.97%) patients were prescribed an oral ß-antagonist of which 441 (28.9%, 95% CI 26.7% to 31.2%) had active asthma and received a new ß-blocker prescription. The average number of patients prescribed rescue steroids at baseline in 367 patients with sufficient follow-up was 3.4 (0.9%) patients every 2 weeks. Rescue steroids were prescribed to 3 (0.8%) patients in the first 2 weeks and to 3 (0.8%) patients in the second 2 weeks following the new oral ß-antagonist (incidence rate ratio (IRR) 0.87, 95% CI 0.25 to 2.99 and IRR 0.89, 95% CI 0.26 to 2.97, respectively). No significant difference was found following stratification for ß-antagonist selectivity. Conclusion: These results suggest that prescribing new oral ß-blockers for the purpose of investigating potentially beneficial effects of chronic treatment would not lead to large increases in patients treated with oral steroids acutely in general practice.