Schwannomas are tumors with slowly progressive symptoms, more often painful than associated with neurologic deficits. Involvement of the sciatic nerve mimics chronic sciatic pain due to a herniated disk. If there is no lumbar pain and lumbar MRI is normal, the sciatic nerve must be clinically and radiologically examined all along its course. We report a patient with chronic sciatica in whom physical examination revealed a painful mass with a Tinel sign in her back thigh. MRI showed a multilobular mass along the sciatic nerve. Surgery of this plexiform schwannoma allowed a complete relief from pain.