High-density polyethylene (HDPE) is a thermoplastic made from petroleum. Deterioration of HDPE materials takes long time due to high molecular mass. In this study, neat HDPE and 5-50% calcium carbonate (CaCO3) reinforced HDPE materials were exposed to different environments for aging. Aging was done in pure water, mineral oil, conventional unleaded gasoline, ammonium hydroxide (NH4OH) and marine conditions. Exposing time of the samples under different liquid medium has been planned for 2, 4 and 6 month periods.After realization of the exposing periods, TMA (thermomechanical analysis), MFI (melt flow index), SEM (scanning electron microscope) analysis were performed. Degradation effect of different aging conditions on characteristics of different weight rate calcium carbonate reinforced polyethylene was investigated. The MFI test results showed that MFI increases with higher calcium carbonate rates. Beside this, TMA test results showed that the glass transition temperature (Tg) decreases with higher calcium carbonate rates. Morphological investigation was done by scanning electron microscope (SEM).