The effect of substitution of clay by sand as well as by-pass cement dust on the physico-mechanicaL properties of clay bricks has been studied. Briquettes were made, and fired for 2 hours at 800°C, then the ceramic properties were studied. The results show that the substitution of 20% clay by sand improves the crushing strength, bulk density and apparent porosity as well as the prevention of bloating of the fired clay bricks. A sand addition over 20% decreases the physicomechanical properties. The addition of 5% by-pass cement dust to the above mix (80% clay and 20% sand) improves the ceramic properties of the fired samples.