Large quantities of sand dunes occur along the NW and SE coastal belts which belong to very low rainfall Dry Zone coasts of Sri Lanka. The orientation depends on monsoonal wind directions, sand supply and wind strength. A scientific study on the dune sand deposits of the NW coastal belt in Sri Lanka was carried out to find out the suitability of the materials to be used for the construction industry in the Island. The distribution, thickness, type of materials and their physical properties were investigated in the field and some other tests were carried out in the laboratory. The laboratory analysis indicates that 95 % of the materials are quartz grains and the balance 5 % consists of a mixture of some heavy minerals, dust, clay, and fine sea shell fragments. Sand of fine to medium size with silt grains are sub-rounded to angular and tabular in shape. The degree of sorting and particle size of dune sands meets the soil properties required in the construction industry. The result indicates that dune sand could be effectively used in construction work without sieving and it is ideal for wall plastering due to its' uniformity. It could also be effectively used in concrete and in mortars mixing with coarse river sand and crushed rock sand.