Crohn's disease (CD) is a progressive disease that is subdivided into three phenotypes: inflammatory, stricturing and penetrating. At diagnosis, most CD patients have inflammatory disease. However, the natural history of CD is one of progression over time to structural complications of the gastrointestinal tract (strictures and fistulae) requiring hospitalizations and surgeries. There is now evidence that early treatment with immunosuppressants and biologics can halt the development of inflammatory damage/fibrosis because of their potential to induce complete mucosal healing. This change in the natural course of CD, mediated by mucosal healing, is associated with a reduction in the incidence of serious complications (those requiring hospitalization and surgeries). Nevertheless, the clinical course of CD varies considerably from one patient to another, and the exact point at which immunosuppressants and/or biologics should be used has not yet been established. Given the difficulty in predicting which individuals will progress to complications and the fact that these therapeutic agents are associated with certain risks (lymphomas and opportunistic infections), efforts are underway to identify the risk factors that will facilitate the classification of patients into high-risk and low-risk groups at the time of diagnosis and to tailor therapy accordingly. This paper is a review of the currently available evidence on the clinical risk factors predictive of CD complications and surgery.