Currently the strongest predictors of disease course in Crohn's disease and ulcerative colitis are the age at diagnosis, disease location and smoking habit. Younger age at the onset is associated with more aggressive disease both in Crohn's disease and ulcerative colitis. Disease location in Crohn's disease is associated with different types of complications: surgery and recurrence in upper gastrointestinal and proximal small bowel disease; and surgery in distal small bowel disease and peri-anal lesions in rectal disease. In ulcerative colitis, extensive colitis is clearly associated with more severe disease. Active smoking globally increases disease severity in Crohn's disease but decreases it in ulcerative colitis. In Crohn's disease, proximal small bowel and upper gastrointestinal tract location is associated with risk of recurrence and surgery; small bowel disease with risk of surgery; and colonic disease, and particularly rectal disease, is associated with increased risk of peri-anal lesions. In ulcerative colitis, extensive colitis is associated with increased risk of colorectal cancer and colectomy. Individual treatment of patients with inflammatory bowel disease depends on disease location and severity. There is increasing evidence that early intervention with immunosuppressives or biologic agents aimed at tumor necrosis factor-alpha usually has rapid and prolonged benefits, including steroid sparing, reductions in hospitalizations and, reductions in the need for surgery.