It is estimated that approximately 25% of the population of the United States participates in recreational boating activities in a given year. These activities result in 7,000 reported accidents, 60% of which result in injuries. Of these injuries, 19% are fatal (11.3% of accidents). Eighteen percent of these fatalities are caused by propellers (2% of accidents). The death toll from boating accidents ranks second among deaths in all modes of transportation. Open motorboats are involved in half of the fatalities recorded. Propeller injuries have an overall fatality rate of 15% to 17%, and a similar rate of major amputations. Experience with nine propeller injuries treated from 1990 to 1996 is presented. The mechanism of production, some technical aspects of propellers, as well as literature on the subject are reviewed. Three patients are described, demonstrating the severity of these injuries, their sequelae, and the challenges they represent.