Reinforced concrete flat slab systems are supported to columns directly without beams. In this analytical study, a structure which has reinforced concrete flat slab with four storey is investigated under earthquake effect. The structure was analyzed by three different methods to compare bending moments in columns and flat slabs. In this study, explanatory information about flat slab systems is presented and different types of solution methods which are adopted our countries specification was compared through a structural example under the horizontal loads. Under the influence of horizontal earthquake forces; selected bearing system have been analyzed by the equivalent frame method, called the moment transfer coefficients method developed by Unluoglu and finite elements method based SAP2000 software. The result of comparing the findings obtained from different solution methods to each other is presented with the help of column top and bottom moments in all floors, flat slab bending moments in inner and edge column strands, tables and graphs. According to this, the method developed by Unluoglu using moment transfer coefficients and the results obtained from finite elements based SAP2000 software are very close to each other. The results obtained from the equivalent frame method are different from those result of the other methods of analysis. Because the equivalent frame method is an approximate method, it does not give as accurate results as the results obtained by the finite element method. However, the method developed by Unluoglu may be an alternative to the finite element method.