An efficient computational technique for nonlinear analysis of reinforced concrete (RC) beam-slab systems (rectangular grids) using grillage analogy is proposed. A load-controlled algorithm has been adopted for tracing the complete load-deflection response till the ultimate load, under monotonic loading. Material modelling of reinforced concrete in the present study includes nonlinear stress-strain behaviour such as cracking of concrete, yielding of steel and tension-stiffening effect. The proposed methodology has been validated against the test data reported in the literature as well as the experiments conducted for the present study. The numerically generated load-deflection curves are found to be in good agreement with the experimental results. The main advantages of this procedure is that it gives a more accurate estimation of short-term deflections under service loads, and a more realistic distribution of moments and shear forces at the limit state of collapse. Further, the algorithm can be conveniently used in reliability analysis of reinforced concrete beam-slab systems.