Early and close monitoring and treatment can slow or prevent disease progression in patients with inflammatory bowel disease (IBD) who are at high risk of developing complications. Therefore, it is important to identify risk factors for complications at the initial diagnosis or during the course of the disease. For patients with Crohn’s disease: young age of onset, extensive lesions, deep ulcers, ileocecal/ileocolonic involvement, perianal and/or severe rectal lesions, and penetrating/stenotic lesions should be considered as high risk factors for complications. For patients with ulcerative colitis: young age of onset, extensive colitis, frequent episodes requiring hormonal or hospitalization increase the risk of colectomy or re-hospitalization. Smoking, comorbidity with primary sclerosing cholangitis, and co-infections may influence the course of the disease. Available genetic markers and serologic markers are not accurate and have no clinical predictive value. Simple general and clinical characteristics may assist clinicians in screening patients at high risk for complications during diagnosis and treatment. However, many of the risk factors are derived from retrospective studies and are not validated, and corresponding prospective studies are needed to provide evidence for clinical decision-making and to truly predict disease progression in each patient.