Risk analysis of slope instability in earth dams is presented using LHS –MC method. Latin hypercube sampling (LHS) is suggested as a tool to improve the efficiency of MC random sampling method. One example of risk analysis for dam slope instability is presented to demonstrate the validity and capability of the proposed method. By means of numerical example, it is shown that about 25% of the calculations can be saved by using LHS –MC method instead of simple MC. The exact savings, however, are dependent on details in the use of LHS and on the shape of the failure surfaces of the problems.