Grisel's syndrome is a unilateral or bilateral subluxation of C1 on C2, associated with an infectious condition in the head or neck. Anatomic studies have demonstrated the existence of a periodontoidal vascular plexus that drains the posterior superior pharyngeal region. No lymph nodes are present in this plexus, so septic exudates may be freely transferred from the pharynx to the C1-C2 articulation. The resulting synovial and vascular engorgements may cause mechanical and chemical damage to the transverse and facet capsular ligaments leading to subluxation. The primary treatment of Grisel's syndrome is medical: the underlying infectious organism must be isolated and appropriate antibiotics prescribed. The subluxation is reduced in halter or skeletal traction. The authors use the classification scheme of rotary subluxation proposed by Fielding, so that treatment appropriate to the specific type of subluxation is used. Based on biomechanical data predicting articular instability and canal compromise proportional to the extent of ligamentous injury, the following specific forms of immobilization are recommended to ensure ligamentous healing: Fielding Type I (transverse ligament intact and bilateral facet capsular injury) soft collar; Type II (transverse ligament and unilateral facet capsular injury) Philadelphia collar or SOMI brace; and Type III (transverse ligament and bilateral facet capsular ligament injury) halo. Following six to eight weeks of immobilization, stability is assessed by the study of flexion-extension roentgenograms. Should residual instability be demonstrated, arthrodesis is indicated.