Reinforced concrete slabs with openings are usually designed with the help of traditional rules of thumb proposed by building codes. Such methods, however, are limited to certain size of opening and magnitude of applied loads. In addition, the load carrying capacity of such slabs depends on the method of strengthening used to compensate for the opening. In existing reinforced concrete (RC) structures, it is often required to create openings in the slabs while these slabs are partially loaded. Introducing openings in slabs can severely weaken the slabs due to the removal of concrete as well as cutting the continuity of reinforcing steel bars. In the present paper, the effect of introducing openings of several shapes (square, rhombus and circle shape) on the performance of two way solid loaded slabs is experimentally studied. Seven RC two way solid slabs with dimensions 1650×1650×80 mm and having central openings were tested under four point static vertical loading. The slabs either had existing openings or openings were introduced under partial loading, after welding the steel reinforcement bars, to be cut to a steel frame provided on the perimeter of the opening. The experimental results show that by welding the steel bars to be cut to a steel frame surrounding the opening, before removing the concrete and cutting the bars, can ensure the same ultimate load like slabs with existing openings. However, the deflections of slabs with introduced openings are higher than those with existing openings. The theoretical study using linear and nonlinear finite element methods show that the calculated deflection values at the ultimate loads are less than experimental values. Finally, the yield line theory gives acceptable ultimate loads predictions matching the experimental values.