The objective of this research is to study the effect of different types of coarse aggregates on the relative bond-slip behavior of coated and uncoated reinforcing bars. It is known that tie application of coating to the surface of a reinforcing bar will decrease the bond capacity by preventing adhesion between the bar and the surrounding concrete, but our interest is to study this decreasing in bond strength with different types of coarse aggregates, concrete strength, and the surface condition and the diameter of reinforcing bars. Epoxy paint coating is applied to the bar to a thickness of around 0.2 mm. Two grades of concrete strength are used. Two types of surface condition of reinforcing bars are considered, the first is smooth surface bars with fy of 24 kg/mm2, the second is deformed surface bars with fy of 36 kg/mm2. The diameters of bars used i i this research are 10, 13, and 16 mm. The bars are tested in 30 cm height and 15 cm diameter concrete cylinder using push in test. The results include the bond strength and bond-slip behavior of specimens. The effect of the considered parameters on bond strength is discussed, and a comparison between the performance of coated and uncoated bars is included.