A surgical simulator for needle biopsy of the spine is being developed in the Radiology Department at Georgetown University Medical Center to assist in learning the procedure as well as to maximize accuracy and efficiency. Spine biopsies are often done under computed tomography (CT) guidance and while this technique is effective, it can be time consuming since the biopsy needle must be advanced slowly and its position checked several times to ensure vital organs are not damaged. Quantifying performance during simulation will allow accurate feedback tot eh surgeon as well as the design engineers. Quantifying performance during simulation will allow accurate feedback to the surgeon as well as the design engineers. Performance measures are also important to determine transfer of simulator training skills to actual surgical skills. The simulation protocol is in advanced development, and the steps include selecting the best CT slice for viewing the lesion, choosing the skin entry point, and advancing the needle to the biopsy location. Our methods for developing the system include the following: 1) A task analysis, which produces a detailed list of tasks needed to complete a goal, their order, and time to completion, 2) A function allocation assessment, which identifies critical task components with the goal of relieving the human workload by a reallocation of system functions, and 3) A simulator evaluation through subjective ratings and objective human performance measures.