The inhibitory effects of acute pain produced by the Lasègue's manoeuvre on the lower limb nociceptive flexion reflexes induced by electrical sural nerve stimulation were explored in patients complaining of sciatica as a result of an identified unilateral disc protrusion. Lassègue's manoeuvre on the affected side produced a typical radicular pain and resulted in a powerful depression of nociceptive reflexes elicited either in the normal or in the affected lower limb. Simultaneously, patients reported relief of the electrically-induced pain. In contrast, painless Lasègue's manoeuvre on the normal side had no effect on these parameters.