Non discal sciatic neuralgia accounts for 5 per cent of all cases of surgical sciatica. They are divided into four groups: central sciatica very seldom, cordal and root sciatica more common and truncal sciatica. These sciatica are dominated by atypical clinical features: atypical provoking factor, atypical character, atypical topography and therapy. A good x-rays study is necessary involving myelography, angiography of the spine etc., but discography and lumbar phlebography are not useful. A rapid review of aetiologies shows that they cover a wide area and that therapy must be debated for each case.