Effects of the casting defects such as micro shrinkage, pore and surface roughness on fatigue properties of cast Ag-Pd-Cu-Au-Zn alloy were investigated in comparison with the fatigue properties of the drawn Ag-Pd-Cu-Au-Zn alloy in this study. Moreover, in this study, cast Ag-Pd-Cu-Au type alloys that were manufactured using a dental casting machine were conducted with two kinds of heat treatments. Fatigue tests were then carried out on these alloys. Relationship between microstructure and fatigue properties was also discussed. The fatigue strength of the cast Ag-Pd-Cu-Au-Zn alloy is considerably smaller than that of the drawn AgPd-Cu-Au-Zn alloy. The size of the micro shrinkage affects the fatigue strength of this cast alloy strongly. The fatigue strength of heat treated cast alloy is greater than of as-cast alloy. The fatigue strength of this cast alloy can be raised by controlling its microstructure through heat treatments. The fatigue crack of the cast alloy initiates preferentially at the micro shrinkage near the specimen surface. The scatter of the fatigue strength of the cast alloy becomes to be small by relating the fatigue life with the maximum stress intensity factor calculated assuming the micro shrinkage that becomes to be a fatigue crack initiation site as a initial crack.