Waste oil palm shell (OPS) is produced in large quantities from the agriculture industry every year. In Malaysia alone, over 4 million tonnes of waste OPS are generated annually. The use of this waste material as aggregates in concrete would help contribute towards a cleaner environment and can also help in conserving non-renewable resources. OPS is lightweight in nature and can be used to produce lightweight concrete. This paper presents the results of an experimental study on the properties of concrete with full and partial replacement of OPS aggregates. In this study, the conventional stone aggregates were replaced with 25%, 50%, 75% and 100% of OPS by volume. The properties of concrete investigated include the workability, 28-day air-dry density, compressive strength, flexural strength and splitting tensile strength. The properties of OPS concrete were also compared with that of conventional concrete (control concrete). It was found that concrete with 100% OPS replacement satisfied the strength and density requirements for structural lightweight.