In this article, transition angle, a new concept for predicting failure mode in orthotropic materials, has been proposed. This angle is introduced as a transition angle from fiber fracture mode to matrix one of orthotropic part. Theoretical calculation of this angle is performed using the concept of microcracks in crack tip damage zone. In order to ensure about the consistency of the proposed approach with the nature of the fracture phenomena in wood, the results obtained from theoretical method are put into contrast with those obtained from practical testing. Transition angle is usable in introducing a safe domain for an angle in loading vector to fiber direction at laminated composite materials and prevents catastrophic failure.