The vibration acceleration levels of various hand held pneumatic tools used under identical working conditions was investigated as part of a NIOSH health hazard evaluation at an aerospace manufacturing company. Data were collected on four consecutive days. Comparisons were available for drills, rivet guns, routers, and sanders. The data indicated that a reduction in vibration was noted for right angle drills with lever throttles. The right angle drill, rivet gun, router, and sander comparisons revealed lower vibration levels for tools cataloged as ergonomic or vibration reduced. The comparisons were based on one specific tool for each model and, therefore, the comparisons may be valid only for the specific combination of the particular tools, workers, and jobs tested. Comparisons would have been more credible if several tools of the same model had been studied. Even so, investigators suggest that the study provides useful information for rating tools based on vibration. Recommendations made suggest that the company continue purchasing new vibration reduced pneumatic tools and replacing older conventional models, that the safety staff monitor the vibration levels of new and old tools to protect their workers better, that the safety staff should apply vibration reducing wrap on high vibration tools until these tools can be replaced, that a medical monitoring program designed for early identification of hand arm vibration (HAV) syndrome be established, and that employees be given breaks from HAV exposures to allow recovery from hand tool vibration.