Background Understanding patterns of socio-economic inequalities in tobacco consumption is key to design targeted public health policies for tobacco control. This study examines socio-economic inequalities in smoking and involuntary exposure to tobacco smoke between 2005 and 2013. Methods Data were derived from the Argentine National Risk Factors Surveys, conducted in 2005, 2009, and 2013. Two inequality measures were calculated: the age-adjusted prevalence ratio (PR) and the disparity index (DI). Educational level, household income per consumer unit and employment status were used as proxies for socio-economic status (SES). Generalized linear models were used in the analysis. Results Prevalence of smoking decreased from 29.7% to 25.1% between 2005 and 2013, mainly in women (p<0.001). Despite the overall prevalence reduction, socio-economic inequalities in smoking persisted. For both men...