1. Two types of spinal extradural cyst are discussed: 1) the type which occurs in adolescents in the dorsal spine with evidence of kyphosis juvenilis; 2) the type which occurs in adults in the dorso-lumbar spine without kyphosis.

2. A fifth case of dorso-lumbar spinal extradural cyst in the adult without deformity is reported. Cysts in this region present common features distinguishing them from the more frequent type which occurs in adolescents.

3. The relationship between spinal extradural cysts, venous drainage of vertebral bodies, and spinal deformity, is discussed.