In this experimental work, the influence of silane coated glass fibres added to polypropylene (PP) and polyamide 6 (PA6) plastics was investigated. These plastics were reinforced with (15 and 30 wt%) silane coated glass fibres. For this purpose, a die was designed and manufactured to produce tension and notched impact species using various injection parameters. Based on the results of this work, which investigates the influence of fibre reinforcement and injection parameters on the tensile strength and impact strength, PP and PA6 plastics reinforced with glass fibre exhibited improvement in their mechanical strength with the fibre reinforcement. However, improvement in the mechanical strength did not show a linear relationship with the fibre weight fraction on account of inhomogeneous fibre distribution and fibre fracture. In addition, tensile strength increased with increasing injection feeding zone temperature and decreased with increasing injection speed and extruder screw speed. (c) 2004 Published by Elsevier Ltd.