The estimated incidence of duodenal Crohn,s disease ranges from 0.5-4% of the patients with Crohn,s disease. However, isolated involvement of Crohn,s disease in the duodenum is very rare, and most duodenal Crohn's disease is accompanied with it elsewhere in the gastrointestinal tract. As clinical, radiographic, and endoscopic features may overlap with those of peptic ulcer disease, patients presenting with isolated duodenal involvement may be perplexing diagnostically. The initial treatment for duodenal Crohn,s diease is medical, but if complications such as gastric outlet obstrution, intractable pain during medical therapy, or hemorrhage occur, surgical intervention is necessary. We experienced one case of isolated duodenal Crohn,s disease showing gastric outlet obstruction without any lesion elsewhere in the gastrointestinal tract and report the case with a review of the literature.