In the present study the laboratory investigations were carried out to study the effect of rest periods on the fatigue life of polymer modified bituminous concrete (BC) mix with Styrene-Butadiene-Styrene (SBS) tri block co-polymer (PMBC) and to compare with control mix of 80/100 neat BC. PMBC mix shows higher fatigue lives when compared to BC mix at different loading ratios, i (ratio of duration of rest period to that of loading). When loading ratios were increased for PMBC as well as BC mixes fatigue lives have been increased. The beneficial effect of loading ratio is higher in case of BC mixes when compared to PMBC mixes. With increase in strain level BC mixes have undergone higher reduction in life ratio (the ratio of fatigue life obtained from fatigue tests conducted with and without rest periods) when compared to PMBC mixes. Increase in life ratio with increase in loading ratio is higher in case of BC mixes when compared to PMBC mixes.