Diagnosis of ulcerative colitis or Crohn's disease is determined by a combined effort of putting together clinical information with several diagnostic tools (endoscopy, histology, radiology, scintigraphy, ultrasonography, and microbiologic and laboratory tests), which can be also used for assessing disease activity. There is now an increased interest toward new entities such as collagenous and microscopic colitis, although the presence of intestinal tuberculosis should be called into differential diagnosis with Crohn's disease. For assessing disease activity, new interest is focused on the serum level determination of cytokines such as interleukin-1, interleukin-6, tumor necrosis factor-α, and others. In patients with long-standing ulcerative colitis, there is a trend to develop strictures, and the clinical course of Crohn's disease is characterized by a frequent need for surgical procedures. Evaluation of health status represents a further effort of better defining the patient's reactivity toward these chronic illnesses, whereas the economic cost might be of great relevance because of the early onset of these diseases. Inflammatory bowel disease patients might complain of several other associated disorders such as hepatobiliary disease, arthropathies, and others, including intestinal and extraintestinal neoplasias.