On April 19, 1995, the most catastrophic terrorist bombing on U.S. soil occurred when the Alfred P. Murrah building was bombed. The bomb blast caused the partial collapse of the nine-story Murrah building, causing 168 deaths and 759 injuries in the immediate area. In the aftermath of the bombing, the State of Oklahoma Health Department conducted an extensive epidemiological data gathering and analysis program. A major aspect of this overall program has been the inclusion of an application built on ArcView 3D Analyst, allowing epidemiologists to query, analyze, and visualize epidemiological data gathered after the bombing. The three-dimensional visualization afforded in 3D Analyst is giving epidemiologists another valuable perspective on their analysis efforts. This application, Oklahoma City Bombing Injury Study (OBIS), is part of a suite of new ArcView GIS-based tools developed as a result of the bombing for overall disaster project management for the first responder community and to enhance the overall level of domestic preparedness. The purpose of the paper will be to present the development, use, and impacts of OBIS and related extensions on disaster management and mitigation.