The etiology of chronic inflammatory bowel diseases (IBD) remains unknown. Understanding IBD epidemiology helps to identify at-risk individuals, to appreciate the changing demographic profile of IBD, and to interpret theories of IBD pathogenesis. This article reviews recent advances in epidemiology and diagnostics. The importance of Clostridium difficile is highlighted. State-of-the-art IBD diagnostic modalities include serology, fecal markers, and advanced radiologic or endoscopic techniques. These include wireless capsule endoscopy, balloon enteroscopy, chromoendoscopy, high-magnification endoscopy, and MRI. The increasing number of available modalities requires appreciation of their indications, strengths, and limitations. This article discusses these issues relevant to the clinician.