Context.-The association between environmental tobacco smoke (ETS) exposure and respiratory symptoms has not been well established in adults. Objective.-To study the respiratory health of bartenders before and after legislative prohibition of smoking in all bars and taverns by the state of California. Design.-Cohort of bartenders interviewed before and after smoking prohibition. Setting and Participants.-Bartenders at a random sample of bars and taverns in San Francisco. Main Outcome Measures.-Interviews assessed respiratory symptoms, sensory irritation symptoms, ETS exposure, personal smoking, and recent upper respiratory tract infections. Spirometric assessment included forced expiratory volume in 1 second (FEV 1) and forced vital capacity (FVC) measurements. Results.-Fifty-three of 67 eligible bartenders were interviewed. At baseline, all 53 bartenders reported workplace ETS exposure. After the smoking ban, selfreported ETS exposure at work declined from a median of 28 to 2 hours per week (PϽ.001). Thirty-nine bartenders (74%) initially reported respiratory symptoms. Of those symptomatic at baseline, 23 (59%) no longer had symptoms at follow-up (PϽ.001). Forty-one bartenders (77%) initially reported sensory irritation symptoms. At follow-up, 32 (78%) of these subjects had resolution of symptoms (PϽ.001). After prohibition of workplace smoking, we observed improvement in mean FVC (0.189 L; 95% confidence interval [CI], 0.082-0.296 L; 4.2% change) and, to a lesser extent, mean FEV 1 (0.039 L; 95% CI, −0.030 to 0.107 L; 1.2% change). Complete cessation of workplace ETS exposure (compared with continued exposure) was associated with improved mean FVC (0.287 L; 95% CI, 0.088-0.486; 6.8% change) and mean FEV 1 (0.142 L; 95% CI, 0.020-0.264 L; 4.5% change), after controlling for personal smoking and recent upper respiratory tract infections. Conclusion.-Establishment of smoke-free bars and taverns was associated with a rapid improvement of respiratory health.