Mechanical properties of Municipal Solid Waste (MSW) play a major role in the stability of landfills. The shear strength properties change with time, temperature and pressure. Due to its heterogeneous behavior, it is very difficult to predict its long-term stability. Therefore, the deterministic approach may lead to either unsafe or conservative design. This paper pertains to a study on the reliability evaluation of MSW slopes under a probabilistic framework. The results of the analysis are compared and discussed in the light of conventional factor of safety approach. It is observed from the study that there is a need to identify the location of critical centre of circle using method of slices when the parameters are treated as random variables. © 2015 Taylor & Francis Group, London.