Considerable research work has been done on the shear strength properties of most soils.rnHowever, very little information is available on the shear strength characteristics ofrnexpansive clays. This is mainly due to the fact that many investigators have concentratedrnmost of their efforts towards finding solutions to the swelling behavior associated withrnthese clays. However, the strength behavior of expansive clays need not be overlooked.rnFactors such as swelling and shrinkage, for example, influence the soil strengthrnsignificantly and their effects are difficult to account for in most laboratory shear tests.rnFurthermore a thorough knowledge of shear strength is required to estimate the bearingrncapacity of expansive clay soils and also to evaluate the stability of dams, road andrnrailway embankments built in these soils areas.rnTherefore, in this paper, Unconsolidated Undrained triaxial shear strength tests werernperformed on unsaturated soil and on some saturated soil samples collected fromrndifferent locations of Addis Ababa, unsaturated soil sample of Gambela and unsaturatedrnsoil sample of five major roads (i.e. Addis-Modjo, Addis-Ambo, Addis-Debreberhane,rnAddis-Weliso and Addis-Ghoastion roads). The purpose of the study was to know thernshear strength properties of expansive soil. Range of values of shear strength parametersrn(cohesion and angle of internal friction) were obtained based on unsaturated soil samples.rnAccording to the outcome of the research, the shear strength of expansive soil rangesrnfrom 30-150Kpa in cohesion and 3-25 degree in angle of internal friction in UU test onrnunsaturated soil. For saturated soil sample in UU test the cohesion ranges from 55-rn94Kpa. There is a decrease in strength in the saturated samples, which shows that therndegree of saturation and the suction pressure can have major influence on the shearrnstrength of expansive soil.