IMPORTANCE: The prevalence of e-cigarette use among US youth increased from 2011 to 2018. Continued monitoring of the prevalence of e-cigarette and other tobacco product use among youth is important to inform public health policy, planning, and regulatory efforts. OBJECTIVE: To estimate the prevalence of e-cigarette use among US high school and middle school students in 2019 including frequency of use, brands used, and use of flavored products. DESIGN, SETTING, AND PARTICIPANTS: Cross-sectional analyses of a school-based nationally representative sample of 19 018 US students in grades 6 to 12 participating in the 2019 National Youth Tobacco Survey. The survey was conducted from February 15, 2019, to May 24, 2019. MAIN OUTCOMES AND MEASURES: Self-reported current (past 30-day) e-cigarette use estimates among high school and middle school students; frequent use (≥20 days in the past 30 days) and usual e-cigarette brand among current e-cigarette users; and use of flavored e-cigarettes and flavor types among current exclusive e-cigarette users (no use of other tobacco products) by school level and usual brand. Prevalence estimates were weighted to account for the complex sampling design. RESULTS: The survey included 10 097 high school students (mean SD age, 16.1 3.0 years; 47.5% female) and 8837 middle school students (mean SD age, 12.7 2.8 years; 48.7% female). The response rate was 66.3%. An estimated 27.5% (95% CI, 25.3%-29.7%) of high school students and 10.5% (95% CI, 9.4%-11.8%) of middle school students reported current e-cigarette use. Among current e-cigarette users, an estimated 34.2% (95% CI, 31.2%-37.3%) of high school students and 18.0% (95% CI, 15.2%-21.2%) of middle school students reported frequent use, and an estimated 63.6% (95% CI, 59.3%-67.8%) of high school students and 65.4% (95% CI, 60.6%-69.9%) of middle school students reported exclusive use of e-cigarettes. Among current e-cigarette users, an estimated 59.1% (95% CI, 54.8%-63.2%) of high school students and 54.1% (95% CI, 49.1%-59.0%) of middle school students reported JUUL as their usual e-cigarette brand in the past 30 days; among current e-cigarette users, 13.8% (95% CI, 12.0%-15.9%) of high school students and 16.8% (95% CI, 13.6%-20.7%) of middle school students reported not having a usual e-cigarette brand. Among current exclusive e-cigarette users, an estimated 72.2% (95% CI, 69.1%-75.1%) of high school students and 59.2% (95% CI, 54.8%-63.4%) of middle school students used flavored e-cigarettes, with fruit, menthol or mint, and candy, desserts, or other sweets being the most commonly reported flavors. CONCLUSIONS AND RELEVANCE: In 2019, the prevalence of self-reported e-cigarette use was high among high school and middle school students, with many current e-cigarette users reporting frequent use and most of the exclusive e-cigarette users reporting use of flavored e-cigarettes.