Fill material performance and its interface friction properties with geosynthetics directly affect the properties of geosynthetics in reinforced earth retaining walls (REW). This paper discusses the performance of cohesive soil and flyash mixture as reinforced earth wall fill material. Laboratory experiments using triaxial testing have been carried out to assess the strength property of cohesive soil mixed with flyash. The results indicate that a mixture of cohesive soil and fly ash has higher strength, rigidity and good interface friction. The technical performance of the mixtures conform to the requirements of geosynthetics reinforced earth retaining walls. Thus this composite filling material can be used in regions where specified graded sand is not available or scarce.