An 18-year-old woman was treated with leukocytapheresis (LCAP) for her combined ulcerative colitis (UC) and aortitis syndrome (AS). Because a close relationship between these two diseases has been suspected based on their etiological and/or pathological findings, we had hypothesized that LCAP, which has satisfactory effects on inflammatory bowel disease such as UC and Crohn's disease might be effective for both her UC and her AS. After informed consent, LCAP therapy was performed once a week for a total of 7 times. Endoscopic remission of the UC was observed. Even though there were no significant improvements in her subjective symptoms of AS such as side-neck pain and dizziness, objective evidence of improvement was obtained when the patient's condition was compared before and after LCAP by angiography, angio-magnetic resonance imaging, and the plethysmogram of her fingertips. These results suggest that LCAP may be valuable as a new adjunct therapy for AS.