In this paper the results of an experimental study on the out-of-plane behavior of steel frames with unreinforced masonry infills (constructed with light hollow clay blocks) with an opening, retrofitted with steel fiber reinforced strips are presented. Large scale test specimens are constructed, prepared, and tested in this study, The test specimens include an unreinforced masonry infill with an opening, a masonry infill retrofitted with steel fiber-reinforced strips in full contact with the surrounding frame, and a masonry infill retrofitted with steel fiber-reinforced strips with no contact with the steel frame. Steel fiber reinforced strips with a width and thickness of 200 mm and 20 mm, respectively are used to strengthen the masonry infills. Hooked-end steel fibers are used to reinforce the concrete overlay. The retrofitting stirps are added on both faces of the walls and anchored with steel rods to prevent premature separation of the concrete layer from the wall. According to the test results, this retrofitting technique can enhance the out-of-plane strength and deformation capacity of the masonry infills. Therefore, it can be used as an effective technique to provide stability for existing unreinforced masonry infills. Moreover, this technique can be utilized to stabilize the masonry infill in new building frames.