Objective To evaluate the effectiveness of Beijing Smoking Control Regulation, occurrence of smoking in restaurants was compared before and after the law took effect.

Methods A cohort study design was used in a randomly selected sample of 176 restaurants in two districts of Beijing. Undercover visits were paid by investigators to the same restaurants at lunch or dinner time 5 months before the law took effect and 1-month after. The occurrence of smoking and presence of no-smoking signs were observed.

Results Much less smoking was observed (14.8%) in restaurants compared to that before the law took effect (40.3%). The drop in smoking occurrence was more evident in open dining areas (from 32.4% to 5.1%) compared to the men's restrooms of the restaurants (23.8% to 18.8%). No intervention from restaurant staff was observed whenever smoking occurred. Posting of no-smoking signage increased considerably after the law came into effect (from 52.6% to 82.4%), but very few no-smoking signs included the symptom hotline number (38.5%) or the amount of penalty (5.6%).

Conclusions The Beijing Smoking Control Regulation achieved one of its intended goals of reducing smoking occurrences in restaurants, but further effort of strengthening implementation is still needed and should focus on boosting compliance with no-smoking sign requirements, reducing smoking in restrooms of the restaurants and mobilising the restaurant staff to intervene in case of violations.