The variation of strength properties of mangium (Acacia mangium) wood treated with the CCA preservative has been studied. It is found that compression parallel to grain, tension perpendicular in radial face and shear parallel to grain in tangential face have been significantly affected by the treatment. The treatment causes reduction in modulus of rupture, stress at proportional limit in static bending and shear parallel to grain. All other strength properties are observed to increase from 3 to 81 percent by treatment.