Epoxide filled composites are being increasingly used for mouldings blocks of hybrid injection moulds. The filling is sought for improving both mechanical and thermal properties that are relevant for the mould performance. In spite of several works investigating the particulate filling of resins, there are only a few reports on fibre reinforcement. Composites based on an epoxy system with varying volume fractions of short steel fibres (SSF) were investigated. The mechanical properties were determined for each composite, and the topography of the fracture surfaces was analyzed by SEM. The mechanical properties of the epoxy filled composites were also compared to commercial particulate composites that are used for producing casting moulds. In spite of the SSF being more difficult to mix that the usual metal particulate fillers, it was found that the resulting composites show some improvement in the mechanical properties.