Red tropical soils are produced by natural chemical weathering. They contain appreciable quantities of amorphous silica and alumina and also large proportions of very poorly ordered clay minerals. For this reason they are considered to be a good source of pozzolanic material and may be used as raw feed for the manufacture of cement or as cement replacement for the production of concrete. This Paper presents the results of an investigation into the engineering properties and performance of concrete made with a mixture of cement/pozzolan, where the pozzolan consisted of two types of red tropical soil. The Paper highlights the strength properties and chloride ion permeability characteristics of these mixtures and discusses the beneficial effects of using red tropical soils in concrete.