Primary superficial leiomyosarcoma is a very uncommon malignant tumor which occurs most commonly the lower limbs. We report one case of unusual topography of this tumor. An 81-year-old female patient presented with a 2 year history of a periungual tumor of the left index finger. The histopathological and immunohistochemical examination of a biopsy specimen was compatible with the diagnosis of leiomyosarcoma. There was no evidence of metastatic disease. An amputation of the index was performed.