Dermatomyositis (DM) is an inflammatory myopathy with a severe prognosis mainly determined by its association with malignancy. We present the results of a study of 32 adults with DM. Our aim was to define predictive signs of cancer and establish prognostic factors according to patient survival. Thirteen (41%) of the 32 patients had DM associated with malignancy. After 7 years of follow-up, the overall mortality rate was 52%. Mortality was higher for patients with malignancy. Cutaneous necrosis and an elevated erythrocyte sedimentation rate appeared as potential markers of associated malignancy. Classic signs of poor prognosis, such as age and association with cancer were found. Interestingly, extensive cutaneous lesions on the trunk and an elevated erythrocyte sedimentation rate were also more frequent among the patients who died. Our results demonstrate that selected groups of patients with DM, in part defined by cutaneous signs, have a poor prognosis.