Lithium-ion (Li-ion) batteries have been powering portable electronic equipment since the mid-1990s. Today, they are ubiquitous in portable electronics, with more than four billion manufactured each year. However, Li-ion batteries are also associated with a spectrum of injuries related to the type of device as well as the person using the device. These injuries range from cutaneous injuries due to flame burns and explosions to corrosion injuries from ingestion. This article describes how the composition of Li-ion batteries can cause injury, the types and extent of Li-ion battery–related injuries, and suggests strategies for prevention.