The article deals with the approach to reliability estimation based on calculations of internal and general stability of MSEW (GRS), taking into account the uncertainty of the initial data. Uncertainty is taken of such ambiguously defined parameters as: the spread of the values of the strength characteristics (from peak to residual strength) of aggregate soils, the design force in the reinforcing layer, the change in the parameters of the interaction of the reinforcing layer with the soil at the ends of the reinforcing elements and the variety of possible surfaces of collapse. The stability estimation is proposed by a probability calcu-lation using Monte Carlo or Hypercube methods. There are two ways to solve the problem of uncertainty of the initial data: 1) probabilistic estimation; 2) numerical simulation. Both approaches can be applied in practice, but require further development and improvement.