INTRODUCTION: a law banning smoking in enclosed public places entered into force in Italy on January 10th 2005. OBJECTIVE: to compare the SHS exposure before and after the coming into force of the new anti-smoking law, with direct measurements in public venues and workplaces. METHODS: vapour-phase nicotine was measured using passive samplers, with personal and environmental sampling. SETTING: samples were collected in 10 municipality offices, 10 industry buildings and 11 public venues (4 discos and 7 pubs) in two towns (Florence and Belluno) from november 2004 to march 2005. RESULTS: during the pre-ban period a wide range of nicotine concentrations was observed. Offices and industry sector exhibited very low concentrations, 0,47 e 0,40 microg/m3 in median, respectively. Highest concentrations were measured in pubs and discos (35,59 and 127,16 microg/m3). After the smoking ban, a noteworthy reduction in nicotine concentrations was found with a stronger effect in pubs and discos (95% of decrease). DISCUSSION: the introduction of a national smoking ban led to a clear reduction in SHS exposure, with stronger results in environments less protected by previous regulations.