We present a 13-year-old boy with a low-grade primary intra-axial cerebral leiomyosarcoma. MRI showed a contrast-enhancing intra-axial mass with features of a cell-rich tumour. The diagnosis was established after neurosurgery and exclusion of an extracerebral primary tumour. The resection of local recurrence 6 months later confirmed the diagnosis, but a higher grade of malignancy was established. The patient died 15 months after the onset of symptoms from general intracranial and intraspinal spread.