We report herein the cases of two patients with Crohn's disease complicated by a psoas abscess. The first patient was a 29-year-old man who underwent definitive surgery after acute inflammation had been controlled by nutritional therapy. In the second patient, a 37-year-old man, the abscess required drainage under local anesthesia prior to surgery. Both patients have been free from recurrence of any abdominal symptoms for about 2 years since undergoing surgery. Although psoas abscess is still regarded as a rare complication, with the increasing prevalence of Crohn's disease in Japan it has become one of the most important complications requiring surgical intervention.