Transverse myelitis is a rare and serious complication of systemic lupus erythematosus (SLE). Magnetic resonance imaging is the investigation of choice for diagnosis and followup. This typically shows T1 and T2 signal prolongation, cord widening, and contrast enhancement over several spinal segments. We describe a 21-year-old woman with SLE who developed very extensive SLE related transverse myelitis with longitudinal involvement of the spinal cord from C3 to T2 and from T7 to the conus medullaris. Clinically, this was manifest as leg weakness, bladder dysfunction, severe low back pain, and patchy lower limb sensory loss. She responded to treatment with pulse cyclophosphamide and high dose corticosteroids with complete recovery in 3 months. To our knowledge, this is the first case report of such an extensive "longitudinal" myelitis.