The objectives of this research were (1) to identify the most hazardous powered and nonpowered handtools used in the underground mining industries (coal, metal, and nonmetal mines), (2) to determine the activities and tool use components associated with the injuries, (3) to use task and ergonomic analyses of the tool use to identify the components of the work that are associated with the injuries, and (4) to investigate ergonomic aspects of the injury and recommend methods to minimize the risk of injury due to tool use. The analysis of a handtool injury data base indicated that underground handtool use injuries frequently involved overexertion injuries to the back. Underground observations of tool use and the subsequent ergonomic analyses identified the components of the tool use sequence that would most likely result in an injury. Biomechanical laboratory studies were performed to understand the nature of the trunk's reaction and the subsequent spine loading due to the use of these tools. Recommendations regarding the tool designs and methods of use have been suggested.