In response to accumulating evidence on the detrimental health effects of second-hand smoke, governments throughout the world have adopted laws prohibiting indoor smoking in public places. Lebanon has recently enacted a law prohibiting indoor smoking in all of its forms, rendered effective as of 3 September 2012. This study examined the knowledge and attitudes of owners/managers of restaurants, cafes, pubs and nightclubs in Beirut towards the ban, three months before it came into effect. Self-administered cross-sectional survey. Data were derived from a self-administered cross-sectional survey conducted in June 2012. In total, 262 hospitality venues (restaurants, cafes, pubs and nightclubs) were sampled at random to participate. The response rate was 74% (194/262). Overall, 84% of owners/managers reported that they were aware of the ban, yet the average knowledge score was only 3.43/10. A general positive attitude was noted towards customer satisfaction (44.8%), law enforcement (61.1%) and employee protection from second-hand smoke (74%), while 55% of owners/managers were concerned that their revenues would decrease. However, 83.3% expressed their willingness to implement the law. This quantitative study is the first to examine the knowledge and attitudes of owners/managers of hospitality venues regarding the indoor smoking ban in Lebanon. Civil society and government bodies should use the findings to develop a campaign to address the knowledge and attitudes of owners/managers of hospitality venues to ensure successful enforcement.