Fly ash, being a by-product of coal fired thermal power plants, creates a potential hazard for the environment all over the world. There will be important environmental benefits if great amounts of such waste material can be used and stockpiles consisting of this waste material can be disposed. In order to utilize fly ash and bring a new alternative to conventional fill materials, fly ash-cement-foam mixture (FCF) has been developed as a lightweight fill material. The FCF mixture attained a typical 7 day strength of 150 kPa with a cement quantity of 130 kg/m(3). The densities of the FCF mixtures varied between 5.20 and 5.60 kN/m(3) in a flowable state. The results obtained from the unconfined compression and CBR tests show that the FCF mixtures have enough strength and durability for using as a lightweight fill material.