Issue addressed: Electronic nicotine delivery systems (ENDS) continue to grow in popularity, particularly among young adults. Understanding by whom various ENDS are being used and why within this population segment can assist the development of appropriate interventions targeting those most vulnerable to use and inform policy decisions in this area. Accordingly, this study assessed the demographic characteristics associated with ENDS use among Australian young adults, and reasons for current e-cigarette use. Methods: An online survey was administered to 1116 Australians aged 18-25 years (59% female). Results: Smokers were more likely than non-smokers to report (a) ever use of ENDS (67% vs 28%), (b) ever use of an e-cigarette (64% vs 24%), e-cigar (17% vs 8%) or e-hookah (15% vs 8%) and (c) current use of e-cigarettes (19% vs 6%). Male smokers were more likely than female smokers to be current e-cigarette users. The most common reason for current e-cigarette use was enjoyment. Conclusions: Young male adults appear to be particularly vulnerable to becoming regular e-cigarette users. This demographic group may need to be a primary focus of prevention and intervention efforts. Contrary to popular belief, smoking cessation was not a primary reason for e-cigarette use. So what?: Greater efforts are needed to educate young adults on the harms associated with ENDS use, especially if use is being driven by the perception that they are a harmless means of amusement. Maintaining existing regulations limiting the accessibility of these products is crucial to ensuring widespread use is minimised.