Malignant nodular hidradenoma , also known as hidradenocarcinoma, is a rare, highly malignant tumor of the eccrine sweat glands. We report a case of a malignant nodular hidradenoma in a 53-year-old woman, who had a 3-year history of enlarging mass on the scalp. Histopathologically, tumor had irregular shape and asymmetrical architecture, showing high cellularity and marked cytologic atypia. We diagnosed malignant nodular hidradenoma based on histopathology. Before she came to our clinic, she had had a surgical excision at other clinic. However, 1 month after the surgery, we diagnosed a recurrence though punch skin biopsy. She had a second wide excision and remaining lesion was removed. There has been no evidence of recurrence or metastasis after the second excision.