Dams are among the largest and most important projects in civil engineering. About thirty-five percents of earth dams failed because seepage through and under dam bodies. In December 4, 1991, the left side embankment of west Nubaria drain at Zawiat Abdoul Kadder village, Egypt, was failed. That failure which may be returned to the blockage effect through the dam material and/or through the filter material on the seepage forces through the embankment. In this study the effect of blockage on seepage characteristics through earth dams has been studied numerically, using a finite element based model (SWICHA), and experimentally, using a viscous flow model (Hele-Shaw), for three cases of earth dams as follows: 1-Earth dam without filter, 2-Earth dam with horizontal blanket filter, and 3-Earth dam with rock-toe filter. The position and the dimensions of the block have been studied. The obtained numerical results are agreed with the experimental ones. The soil blockage in earth dams is considered as a one of typical reasons for earth dams failures, so this study should be especially useful to professionals in Hydraulic Structures, or anyone else who may be interested in Irrigation Works.