PurposePreventive health behavior during COVID-19 protects not only oneself but also the welfare of others. However, little attention has been paid to prosocial motivation in adolescents, who are often viewed as selfish and egocentric. Therefore, the current study aimed to explore the role of empathy in adolescents’ preventive health behavior using longitudinal data. MethodsA total of 442 Chinese adolescents (mean age of youth = 13.35 years; 49.5% girls and 50.5% boys) completed two-wave longitudinal surveys over the span of two months during the pandemic (Time 1: July 2020; Time 2: September 2020). At T1, participants reported on their empathic concern, perspective taking, and concern for personal health. At both T1 and T2, participants reported on their preventive health behavior and COVID-related worry. ResultsAdolescents who showed greater empathic concern tend to engage in more preventive health behavior over time (p < .01). However, greater empathic concern also predicted adolescents’ greater worry about COVID-19 over time (p < .01). In comparison, adolescents’ perspective-taking and concern for personal health did not predict their health behavior or worry over time. Notably, the longitudinal effect of empathic concern on preventive health behavior and COVID-related worry remained (ps < .05) after taking into account adolescents’ perspective-taking and concern for personal health. ConclusionsThese findings highlight adolescents’ prosocial motivation in engaging in preventive health behavior during the pandemic and also point out the potential negative influence of empathic concern on adolescent mental health.