Purpose: Youth electronic cigarette (e-cigarette) use remains high in the USA, and advertising is a contributor. The purpose of this study was to identify themes and characteristics of popular e-cigarette companies' advertising after e-cigarette companies became more highly scrutinised in 2018., Methods: Using a systematic, quantitative content analysis, three trained coders coded e-cigarette advertisements from JUUL, Puff Bar, Vuse and Blu from 2019 and 2020. Based on previous work, they coded for: type of advertisement, flavours, promotions, product cues, descriptors, claims, imagery, youth-oriented themes and sensational appeals., Results: Of the 401 e-cigarette advertisements, the majority were emails (38.2%) and Instagram posts (30.9%). Over half (53.6%) showed flavours other than tobacco, with Puff Bar leading the brands (70.2%; p<0.001). The most frequently used product cues were showing the product (51.4%) or packaging (42.4%). The most common claim was being an alternative to smoking (14.2%). The most frequently used imagery was fruit (14.0%), employed most by Puff Bar (p<0.001). The only youth-oriented theme present was humour (4.2%). Positive sensations (eg, good taste, good smell or satisfying; 17.1%) was the most common form of appeal, with Puff Bar using it at the highest frequency (p<0.001)., Conclusion: Even with heightened scrutiny of e-cigarette brands, advertisements still included youth-appealing content such as flavours, fruit imagery and positive sensations. Puff Bar led in all these categories, and it rapidly gained market share after market leader JUUL limited the sales of its flavoured products. Research should continue to monitor the characteristics of e-cigarette advertisements and consider their impact on youth., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2023. No commercial re-use. See rights and permissions. Published by BMJ.)