One of the most promising current options for lowering the cost and environmental impact of cement is the use of blended cement. Well-established supplementary cementitious materials such as slag and fly ash are limited in most African countries. In Tanzania, a promising option lies in the production of LC3 binders. In this research, the suitability of kaolinite clays from two selected deposits in Tanzania for clinker replacement was assessed and compared with a reference sample from South Africa. Results indicate that both Tanzanian clays are suitable, based on the kaolinite content. However, factors such as the internal surface area of the clay also influence its performance.