A 42-year-old woman first received the diagnosis of systemic lupus erythematosus at our hospital in 1986. Thereafter, she noticed a small subcutaneous nodule on her left leg. This nodule became larger, and many new nodules appeared. Some of these were amassed to form large, flat, platelike tumors. Roentgenographic and histological examination revealed that they were calcium deposits. To our knowledge, this is the first report of very large, hard tumors resulting from calcium deposition in the skin.