Several hybrid structures which have been developed are reported in the literature. Whether any of these have appeared in commercial applications is unknown to the author. For critical applications such as aeronautics a considerable amount of additional testing needs to be done. In most cases the reason to keep metals in the hybrid structure seems to be to keep costs down although in some cases the goal is to combine the properties of metals and composites. As composites become cheaper the need for hybrid structures might decrease. Among hybrid materials fiber metal laminates is by far the most interesting class of materials and among different fiber metal laminates GLARE is used in the fuselage of A380. If it would be possible to create a corrosion-resistant material using carbon fiber composites together with aluminium, CARALL, a very competitive material would be the result. In addition hybrid joints show interesting results. But, the cost associated with manufacturing the material will probably be high, making the approach interesting only for highly loaded joints. Radar absorbing composites is an interesting application which might be used in the future. Since the reflection loss peak is narrow, further development is needed to broaden the peak or a good understanding of any future threat-radars frequency is required.