We report the first case of limited cutaneous Kaposi's sarcoma during ulcerative colitis, in a HIV-negative 68 year-old man without any risk factors for this tumor. In our case, the steroid-therapy necessitated by the colitis is the most important aetiological factor of the sarcoma and its withdrawal leads to a complete remission of the tumor. The link between steroid-therapy and Kaposi's sarcoma is well known. A link between ulcerative colitis and Kaposi's sarcoma can be discussed but not proven. The possible occurrence of this cutaneous tumor during ulcerative colitis is of interest.