Compressive strength, density and dynamic elastic modulus of mortar reinforced with wood sawdust wastes (WSW) were investigated. Additions of 0, 0.5, 1 and 3% by weight of (WSW) were used. The mechanical influence of sawdust was followed after 7, 30 and 90 days of curing. Scanning electron microscope (SEM) was used to characterize the morphology of the composites and to find the adhesion behavior of sawdust. The results show that compressive strength increases with sawdust content up to 0.5%. Using sawdust content larger than 1%, produces mortars with an excessive loss of compressive strength, especially for 3% of WSW. Lightweight mortar was obtained only for 3% of WSW reaching a compressive strength of almost 25MPa after 90 days of curing. According to SEM results, a good adhesion was originated for 0.5 and 1% of WSW and for all WSW percentages used a positive effect on the post-cracking behavior was found.