To describe the prevalence of e-cigarette users who use them in selected indoor public and workplaces, and private venues in Barcelona (Spain) in 2015.This is a cross-sectional study of a sample of e-cigarette users (≥ 18 years) from Barcelona (n = 600). We calculated the proportion of e-cigarette users who used the device in public and private settings (in the last 30 days). We fit multivariate logistic regression models adjusted for sex and age to calculate the odds ratios (OR) with their 95% confidence intervals (CI) of e-cigarette use by socio-demographic factors, dual use and nicotine-containing e-cigarettes.The highest proportion of e-cigarette users who used them in public places was found at restaurants or bars (69.4%) and nightclubs or pubs (55.4%). Also being current conventional tobacco smokers (dual users) was significantly associated with lower use of e-cigarettes in workplaces (OR = 0.61, 95%CI:0.41–0.91), restaurants (OR = 0.66, 95%CI:0.45–0.97) and nightclubs (OR = 0.56, 95%CI:0.37–0.86). Moreover, being a nicotine-containing e-cigarette user was associated with higher odds of using the device in workplaces (OR = 2.01, 95%CI:1.34–3.01), and lower odds of using it in nightclubs (OR = 0.56, 95%CI:0.39–0.82). 96.8% of the included e-cigarette users declared to use the device at home. Being a current tobacco smoker was associated with increased odds of using e-cigarettes at home (OR = 3.17, 95%CI:1.22–8.22).E-cigarette use in private settings and in public settings where their use is not regulated by law is high. Therefore, the public health administration in Spain should consider expanding the prohibition of e-cigarette use to indoor public places and should take into account the possibility of exposure to aerosol from e-cigarettes.