This paper presents some results of ongoing laboratory work to design a lightweight concrete using colemanite waste and pumice. Hisarcik and Espey colemanite wastes, acidic pumice aggregate as well as normal Portland cement were used to produce lightweight concrete with economic and environmental advantages. Two different groups and twenty different prescriptions were tried to produce lightweight concrete. The effect of colemanite waste on workability and strength of lightweight concrete were analysed by fresh and hardened concrete tests. The properties of materials examined include slump, air content, density and uniaxial compressive strength of the mortar. The results obtained were compared with control concrete properties and Turkish standard values. The examined tests results showed that lightweight concrete can be produced by the use of acidic pumice aggregate and colemanite waste. Furthermore, the colemanite waste can be used as cement additives and can reduce the cost and environmental pollution with using natural stone aggregate.