Upper gastrointestinal (GI) tract inflammation in inflammatory bowel disease has become increasingly recognized, even in the absence of specific localizing symptoms, as patients more frequently undergo upper endoscopy. Although the recent Montreal classification system allowed classification of upper GI involvement in Crohn's disease (CD), independent of other locations, a consensus regarding the definition of what qualifies as significant "involvement" is still lacking. Reported incidence data vary considerably depending on the definitions used and the selected target population. Pediatric data suggest that upper endoscopy is useful in differentiating CD from ulcerative colitis, when inflammation is otherwise predominantly confined to the colon; however, this question has yet to be studied in adults. Infliximab therapy for upper GI-CD seems as effective as that seen for more distal GI inflammation.