Abstract: The invention concerns an interspinous stabilizer comprising two members anchoring it to spinous processes of two respective vertebrae, and a body extending along a direction aligning the members, the body, being compressible along the alignment direction by the effect of stress based on a predetermined configuration, the body being adapted to recover spontaneously said predetermined configuration after the stress has ceased, the body comprising a leaf spring with a geometrical generatrix. The anchoring members are capable of fixing the stabilizer to the spinous processes such that the generatrix extends substantially from the front to the rear relative to the patient's body.