<b>Expermential Investagation and Analysis of Bitumen Modifaction Using Fly Ash</b> The increase of crude oil prices in recent years resulted in an increase in bitumen prices as crude oil is origin for bitumen, asphalt and in other hand the fly ash from the power generating plants causes severe disposal problems. The main purpose of this project is to study the possibility of using fly ash as mineral filler in Bituminous paving mixes. Fly ash, a coal combustion product once treated as waste and disposed in landfills, is used today in substructure and road works. The research of fly ash properties may solve the problems of treatment and intelligent use of this residual material. This Marshall stability test is employed to determine the properties like stability, flow value, air voids, voids in mineral aggregate VMA , voids filled with bitumen VFB for a Dense Bituminous Macadam DBM mix. The experimental work is carried out by using specifications from MORTH Ministry of road transports and highways, specifications for road and bridge works,5th revision .By replacing the stone dust with fly ash at the levels 4 , 6 and 18 the results are compared. The variation of properties, optimum bitumen and fly ash contents are evaluated. It is observed that the mixes with fly ash as filler not differ much in properties when compared with control mix and satisfy desired criteria specified by a much higher margin. Hence, it has been recommended to utilize fly ash wherever available, not only reducing the cost of execution, but also partly solve the fly ash utilization and disposal problems. Bitumen, Fly Ash, Dense Bituminous Macadam, Marshall Stability Test 1115-1119 Issue-5 Volume-4 Mohammad Ather Ul Jahangeer | Er. Pannu Ovais Manzoor | Er. Sajad Ahmad Mir