This investigation focuses on fiber damage during processing and the effect of fiber length and fiber content of basalt fiber compounds on mechanical properties. A composite of basalt fibers (BaF) and Polypropylene (PP) is compounded with a twin-screw-extruder and specimens are fabricated via injection molding. Fiber contents and process parameters are varied in extrusion and injection molding processes. Fiber lengths and contents in specimens are determined and correlated with tensile strength, tensile modulus, impact strength and elongation at break. The investigation of the processes regarding fiber damage is necessary for determining achievable fiber length in moldings and resulting mechanical properties.