Abstract: In this study, we investigate the effect of broom fiber incorporation and its surface treatment with stearic acid on the mechanical and rheological (melt flow index) properties of polymeric composites based on Polypropylene/Broom fiber. The results obtained show that in the case of composites with untreated broom fiber, the highest tensile properties and impact strength (Izod) are obtained for a fiber content between (10-20 wt%). For the composites with treated broom fiber, these values are shifted to fiber content of about (30 wt%). The melt flow index (MFI) show certain increase with increasing the content of stearic acid.