This paper investigates the effect of uncertainty in the hydraulic conductivity and van Genuchten fitting parameters used for unsaturated flow modeling of transient seepage through embankment dams. Random variables of the parameters are generated using a number generation algorithm and are then coupled with the finite element software SEEP/W. Stochastic analyses are conducted via Monte Carlo simulation. The statistical and probabilistic properties of the seepage rate passing through different embankment dams and transient boundary conditions are assessed and the degree of uncertainty associated with the seepage is evaluated. It is found that the probabilistic properties of the seepage strongly depend upon the boundary conditions of the dam. The seepage through embankment dams is found to follow the generalized extreme value or three-parameter lognormal distributions. (C) 2017 American Society of Civil Engineers.