For architectural or environmental reasons, openings sometimes are required inbearing block masonry walls. These openings which may have any size or location surelyaffect the mechanical behavior of such walls since they create some sort of stressconcentration around the corners. The existence of openings in bearing block masonrywalls does not only cause a change in the structural behavior but also reduces both thecracking and ultimate loads.In this study the effect of existence of square and rectangular openings in bearingblock masonry walls on the behavior of such walls was studied numerically using thefinite element method. Forty eight different models were tested to study the effect of theinfluencing parameters such as the size and location of the openings, wall sides boundaryconditions, . and type of loading on the wall behavior. Also the effect of loss of supportwas investigated.Linear elastic fracture mechanics based on pre-finite element and photoelasticityresults was carried out in this study in order to check the reliability of using suchmethods for predicting the ultimate load capacity of concrete block masonry walls withopenings and to investigate the possible propagation of cracks around the openings. Atotal number of forty walls were tested using the finite element and fracture mechanicsmethods in which the opening shape and size, type of underlying soil and the sidesboundary condition were varied. Photoelasticity method was also used to -investigate thebehavior of nine bearing block masonry walls.The experimental and numerical results were ’compared to each other and toanother identical wall with no openings in order to clarify the resulting differences in themechanical behavior. Results showed that the fracture mechanics- finite element resultsand the photoelasticity results were only 10% away of each other. The effect of differentstudied parameters were also found to be significant.Bearing wall structures usually show brittle behavior under loads. Due to theexistence of high vertical or lateral loads, bearing walls permit cracks in variousdirections. These cracks which vary in locations, directions and lengths surely affects themechanical behavior and bearing capacities of the walls.In this study, the effect of the above parameters on the behavior of bearing solidwalls resting on different types of soils and having an edge loss of support and differentsides boundary conditions were also investigated using the finite element method. Fiftytwo models were tested. Results were compared to some other identical walls with nocracks, in order to clarify the resulting differences in the mechanical behaviorUseful conclusions and recommendations concerning the behavior and loadbearing capacities of such walls which could help very much designing of such walls wereobtained.