Different aspects of the relationship between dermatopolymyositis and cancer of the ovary are emphasised here. A clinical case support these aspects. In the incidence of cancer of the ovary it is remarkable that there is often a relationship between the two conditions. Usually the diagnosis of the dermatopolymyositis comes before the cancer is discovered. This means that decisions have to be taken as to how far investigations for the cancer should be carried out when dermatopolymyositis has been diagnosed.