We report a case of myelitis after plasma-derived hepatitis B vaccination. The patient was a 31-year-old man who presented with progressive sensory symptoms in extremities that developed 2 weeks after a third vaccination. MRI of the cervicothoracic region revealed swelling and T2 high signal at the level of C4 to C5 cord, and isolated enhancement in the posterior columns between C4 and C5 cord. The significance of MRI findings and HLA haplotype of the patient will be briefly discussed.