Transverse myelitis is a rare and serious complication of systemic lupus erythematosus (SLE). Magnetic resonance imaging (MRI) shows cord swelling and increased signal intensity in T2-weighted images in a patient with transverse myelitis. We described a 45-year-old man presenting with weakness on the lower extremities without involvement of the upper extremities, as an initial manifestation of SLE. The lesion was involved continuous levels of the cervical spinal cord, a distinctive feature recently named `longitudinal myelitis`. His symptoms and signs responded well to the cyclophosphamide and methylprednisolone pulse therapies. So far, 10 cases of longitudinal myelitis have been reported in the world. But only 2 cases presented lower extremities weakness rather than upper extremities, in spite of cervical spine involvement. We report a patient with longitudinal myelitis in the cervical cord presenting weakness of the lower extremities as an initial manifestation of SLE with literature review.