Dermatomyositis is a rare inflammatory myopathy that has characteristic cutaneous lesions. Although many malignancies are associated with dermatomyositis, urogenital malignancies have rarely been reported to be associated with dermatomyositis. We report here on the first case of ureteral cancer associated with dermatomyositis. A 42-year-old man presented to us with a skin rash. A clinical diagnosis of dermatomyositis was made due to the skin lesions, muscle weakness, arthralgia, the increased erythrocyte sedimentation rate and the increased creatine kinase level. The patient revealed microscopic hematuria and abnormal urine cytology during the investigation for the underlying malignancy. Retrograde pyelography demonstrated a suspicious lesion in the right mid-ureter, and the ureteroscopic biopsy revealed the urothelial carcinoma. Although an operation was recommended, the patient died of pneumonia associated with his interstitial lung disease, which is one of the poor prognostic indicators of dermatomyositis.