The compsns. contain (A) 100 pars silicone resin with m.pt. of 25 - 200 degrees C by the Durran Hg method, and contg. 1 - 1.7 org. gps. and >=0.25 wt.% OH gps., directly attached to silicon atoms, (B) 50 - 200 parts glass fibres of 0.2 - 10 mm. length (C) 10 - 200 parts of >=1 inorg. filler and (D) a hardening catalyst. (B) pref. consists of 100 - 200 parts glass fibres with lengths of 0.2 - 6 mm. and the compsn. granules are pref. 0.4 - 4.7 mm. size. The compsns. are suitable for compression, injection or transfer moulding or for extrusion, giving products with increased mechanical strength esp. impact resistance.