Reported herein is a case of hepatocellular carcinoma (HCC) occurring in a 25-year-old Japanese man who was diagnosed with Crohn's disease (CD) at 14 years of age; treatment included predonisolone, azathioprine, and infliximab. The tumor was located in right upper lobe and the size was 8 cm in diameter; histology was poorly differentiated HCC with pleomorphic cellular changes. Adjacent normal liver showed no evidence of cirrhosis or viral hepatitis. Until now, only six cases of HCC arising in patients with CD have been reported in the English-language literature. Most of these patients had early onset of CD and HCC: none had cirrhosis or virus hepatitis. Most patients had a long disease history of CD and were being medicated with several immunosuppressive agents. Some factors associated with CD might indirectly or directly be related to the development of HCC in CD patients, although the possibility that these HCC occurred coincidentally in CD patients, including the present patient, cannot be ruled out. Accumulation of cases is necessary to evaluate the relationship between CD and HCC precisely.