We report a rare case of a 32-year-old Caucasian man who presented with a 2-month history of progressive proptosis in his left eye with no visual impairment nor diplopia. He had suffered from ulcerative colitis for 3 years before presentation. Computed tomography and magnetic resonance imaging scans demonstrated mild proptosis and isolated enlargement of the left superior rectus muscle. Laboratory examination results showed no evidence of other ocular or systemic disease. He was treated with a short course of systemic steroids. His intestinal and eye conditions quickly improved over the following weeks. After a 1-year follow up, the orbital myositis remains unchanged and the digestive condition is satisfactory with a long-term mesalazine therapy. To our knowledge fewer than 10 cases of orbital myositis associated with ulcerative colitis have been reported in the literature. We present and discuss a new case with a concomitant evolution between these two disorders.