Cigarette warning labels are important sources of risk information, but warning research for other tobacco products is limited. This study aimed to gauge perceptions about warnings that may be used for e-cigarettes. We conducted six small focus groups in late 2014/early 2015 with adult current e-cigarette users and cigarette-only smokers. Participants rated and discussed their perceptions of six e-cigarette warning statements, and warnings in two existing Vuse and MarkTen e-cigarette ads. Participants were open to e-cigarette warnings and provided the strongest reactions to statements warning that e-liquid/e-vapor or e-cigarettes can be poisonous, contain toxins, or are “not a safe alternative to smoking”. However, many also noted that these statements were exaggerated, potentially misleading, and could scare smokers away from reducing their harm by switching to e-cigarettes. Opinions on the Food and Drug Administration’s proposed nicotine addiction warning and warnings that e-cigarettes had not been approved for smoking cessation or had unknown health effects were mixed. Participants perceived MarkTen’s advertisement warning to be stronger and more noticeable than Vuse’s. Care should be taken in developing e-cigarette warnings given their relative recentness and potential for harm reduction compared to other tobacco products. Additional research, including with varied audiences, would be instructive.