Speed, ease of use, and ready availability have made pneumatic nail guns a common tool used in work settings such as residential construction and wood-product fabrication. In addition, the tools are now readily available to consumers, extending to the public what had been primarily a potential work-related hazard. To characterize nail-gun injuries in work and nonwork settings, patients with nail-gun injuries treated in U.S. hospital emergency departments (EDs) were studied by using the U.S. Consumer Product Safety Commission's (CPSC's) National Electronic Injury Surveillance System (NEISS) and the NEISS occupational injury supplement (NEISS-Work) maintained by CDC's National Institute for Occupational Safety and Health (NIOSH). This report describes the results of that analysis, which indicated that during the 5-year period 2001-2005, an average of approximately 37,000 patients with injuries related to nail-gun use were treated annually in EDs, with 40% of injuries (14,800) occurring among consumers. In addition, data on ED-treated injuries indicated that, in 2005, nail-gun injuries among consumers were approximately three times higher than in 1991 (4,200). Additional measures are needed to prevent nail-gun injuries among both workers and consumers.