Although concurrent occurrence of spondyloarthritis (SpA) and ulcerative colitis (UC) is sometimes seen, the profiles of cytokines have been poorly understood in UC-associated SpA. We herein report a case of UC-associated SpA successfully treated with infliximab. Profiles of cytokines in the serum and colonic mucosa were characterized by an enhanced expression of IL-6 but not TNF-α. Successful induction of remission by infliximab was associated with the downregulation of IL-6 expression but no significant alteration in TNF-α expression. These findings suggest that some cases of UC-associated SpA might be driven by IL-6, and infliximab might be effective in cases lacking enhanced TNF-α responses.