Door beams are attached inside car doors as one way to protect passengers from shock when the car is side impacted. Though door beams made of high tensile strength steel predominate now, the use of aluminum is growing rapidly to reduce weight. The effects of cross-section and types alloy on the performance of aluminum extrusions as door beams were investigated. As the result, aluminum door beams were developed which have bending proper2ties comparing favorably with those of door beams made of high tensile strength steel with a tensile strength of 1470 N/mm2. Since the shape of the cross-section of aluminum extrusions is versatile, non-symmetric cross-sections composed of regions with different wall thicknesses and lengths can be produced. On the basis of this technology, a technology to design door beams with required bending properties for any car model was developed. This technology is already been utilized in various automobiles. In this paper, the characteristics of these newly developed aluminum door beams will be introduced along with the results of practical use of them .