Due to the significant increase in the demand for eco-friendly materials, conventional concrete and mild steel have become less recommended due to the excessive CO2 emission of conventional concrete and corrosion issues of mild steel. Thus, other eco-friendly alternatives have risen to partially replace these two materials. The first alternative is glass fiber reinforced polymers and the other is high volume fly ash concrete. This study investigates the bond-slip performance of glass fiber rebars implanted in conventional and high volume fly ash concrete. The results were then compared to bond-slip results yielded from using mild steel. A total of twenty four cylinder specimens were tested in this study. Two levels of high volume fly ash replacement of cement were used, 50% and 70%. Additionally, 13 mm (1/2 in.) and 19 mm (3/4 in.) glass fiber and mild steel rebars were investigated. The study was conducted following the recommendation of RILEM. The results indicated that, regardless the type of concrete, glass fiber had less bond strength than that resulted from using mild steel.