Cutter roof failure is a common failure mechanism in coal mine roadways due to the oblique orientation of the major horizontal stress with respect to roadway advance direction. In the present study, two 3D numerical models based on the discrete element method have been developed to simulate cutter roof failure. In the first model created using PFC3D, the rock surrounding a roadway is represented by an assembly of spheres glued together at their boundaries. High horizontal stress at varying orientations to the roadway advance direction is applied to the model to investigate the mechanism of fracturing around the roadway. The numerical results indicate that a roadway driven at a large angle (75 degrees-90 degrees) with respect to the maximum horizontal stress suffers significantly more fracturing than that driven at a small angle (0-15 degrees). The second model created using the distinct element code 3DEC adopts a newly developed Trigon logic in which the roadway roof is represented by an assembly of tetrahedral blocks bonded together at their contacts. Both the PFC3D and 3DEC models successfully simulate the cutter roof failure process which is characterized by a fracture zone initiating at the corner where the major horizontal stress and the roadway roof intersect: this fracture zone propagates across the roof span with continued roadway advance. The influence of pre-existing fractures is evaluated in the PFC3D model and the results show that incorporating bedding planes and cross joints in the roadway roof promotes the development of distinct cutter roof failure immediately behind the advancing face. The numerical results presented provide additional insight into cutter roof failure mechanisms and important insight for guiding design and layout of roadway support. (C) 2013 Elsevier B.V. All rights reserved.