Although orthognathic surgery has now become a routine part of oral and maxillofacial surgery practice, the complexity of such surgery together with the detailed planning involved makes it a difficult area of surgery to follow in the literature. The plethora of literature on the subject of complications in orthognathic surgery makes it essential to devise a simple classification of complications so that comparative studies can be identified and grouped together for more meaningful interpretation. The aim of this article is to present a brief and coherent overview of the main complications associated with orthognathic surgery for the purpose of establishing a simple classifciation of complications for future reference.