The patient, a 30 year-old man, dentist, started having an influenza-like infection which lasted five days, with malaise, muscle pain throughout the body and fever- One day before the hospital admission he presented urinary retention followed in the next day by ataxia and numbness sensation in both feet and lower third of his legs. The neurological examination disclosed a thoracic spinal cord impairment at T9-T10 level and the diagnosis of a post- infectious transverse myelitis was made. The plain Rx of the spine showed a spina bifida oculta in the T7 vertebra, which is roughly at the same level of the T9-T10 spinal cord segment. An iodinated myelography showed no abnormalities. The CSF examination showed small increase in the white cells (6.4 cells/cu.mm). The patient received dexamethasone (4.5g/day) and two weeks later was entirely free of symptoms. The authors think that the congenital bone defect (spina bifida) might have played a role in the development of the myelitis, probably because of an ontogenetically determined "vulnerable point" ("locus minor resistentia") at that level, either anatomical or immunological.