In this study, mechanical and physical properties of cement mortars containing marble dust and glass fiber in various combinations were investigated, in addition to analyzing the corrosion behavior of reinforcing steels embedded in these mortars. To this end, cement mortars containing glass fiber (0 kg/m3, 0.25 kg/m3, 0.50 kg/m3 and 0.75 kg/m3) were prepared. Besides, with the purpose of determining effect of marble dust addition on the corrosion resistance of the glass fiber reinforced mortars, marble dust were added to all series by substituting with filler sand at proportions of 0%, 10%, 30% and 50% by volume. Corrosion studies were carried in two stages. Firstly, corrosion potential of reinforcing steels in the mortars was measured every day for a period of 150 days based on the ASTM C-876 standard. Secondly, cathodic polarization values of the steels were obtained by using the Tafel extrapolation techniqueand subsequently corrosion current densities were determined. Thanks to the study, it was observed that a decrease in the corrosion resistance of the mortars had taken place as a result of glass fiber addition. But, it was determined that with the addition of marble dust into the mortars, corrosion resistance of the specimens was significantly increased.