The association between ulcerative colitis and Takayasu's arteritis has been well described in patients of Asian ethnicity. We present the third non-Asian case reported in the English literature, of a 37-year-old woman with a 4-year history of Takayasu's arteritis, who developed idiopathic ulcerative colitis. She was found to carry the human leucocyte antigens HLA-B52 and DR2, which have been previously noted to be associated with these inflammatory conditions, mainly in the Japanese population. Ulcerative colitis was steroid-dependent despite simultaneous administration of mesalazine. Azathioprime achieved remission of both diseases. The possible pathogenic association of the disorders is discussed.