In this study, effects of polyiner and fiber modification on low temperature properties of bituminous mixtures Were studied. One aggregate, one asphalt binder type, three additives (polymer, synthetic fiber and loose cellulose fiber) and three 85 degrees C oven aging levels (0, 5 and 25 clays) were considered. The thermal stress restrained specimen test (TSRST) was used to evaluate the low temperature cracking resistance and aging performance of modified asphalt concrete specimens. The analysis of covariance was performed using a general linear model (GLM) procedure On the TSRST results by using statistical analysis system (SAS) software. Aging levels and type of additive were determined as most important factors that affect fracture temperature and fracture strength. Fracture temperature becomes warmer with the increase in the degree of aging. It was observed that fracture temperature and fracture strength change according to additive type used.