In this paper the present day state-of-the- art relevant to the estimation of the reliability of the plastic slabs is presented. It is shown here as to how the concepts of the modern structural reliability theory developed in the recent past are applied to the design analysis of the plastic slabs including reinforced concrete slabs which are under reinforced. The safety margins established on the basis of upper bound, lower bound and exact load carrying capacities of the reinforced slabs are used in the reliability estimate.