This research studies the effect of adding sawdust as waste from carpentry factory to concrete mixes quantity with cement contents 300 and 350 Kg/m³ to produce concrete blocks which could be used in the construction field in its both types of solid with dimensions of 400 * 200 * 150 mm and hollow with dimensions of 400 * 200 * 200 mm. The sawdust material treated with oil of engines (burned) through immersed in it for 24 hours and then dried to avoid any effects of organic materials for different percentage ranged between (10 %to 30 %) by weight of cement. The influence of sawdust material on the mechanical properties of concrete block, compressive strength, absorption ratio and insulation thermal has been verified. The obtained results were compared with a concrete blocks mixes with the same amount of reference cement without adding any sawdust ratio. The results indicated that using sawdust as cement replacement enhances the thermal insulation of concrete mixtures. Results showed also that the thermal conductivity decreased with increasing sawdust ratio for all concrete mixes. The decreasing ratio ranged between 27 % and 56 % of reference mixes, respectively. The obtained results show that the thermal conductivity doesn't effected by increasing the cement content. On the other hand, using of sawdust in concrete mix reduces the strength of concrete with ratio ranged between 8.8% to  49.3 % and 9.8 % to 46.4 % of reference mixes, respectively.