The clinical and light and electron microscopic features of five cases of primary vaginal leiomyosarcoma, representing 2.9% of all vaginal malignancies registered at the Swedish Cancer Registry, are presented. The ages of the patients ranged from 31 to 69 years. The most common clinical presentation was an increasing mass and/or local tenderness. The tumor was located in the anterior wall in three cases and in the lateral wall in two. The size of the tumors ranged from 2 to over 10 cm. Four patients had tumors of high histologic malignancy grade and were all dead within 36 months. One patient had a tumor of low grade and is still alive 10 years after the initial excision. The ultrastructural observations of abundant myofilaments with focal elongated densities in primary paraffin-embedded material conform with the light microscopic diagnoses in all cases and indicate the usefulness and value of such material for electron microscopy in order to arrive at the diagnosis of leiomyosarcoma. The therapeutic and diagnostic aspects are discussed.