In intact or decerebrate pigeons, unilateral functional deafferentation of the dorsal neck muscles of one side produced a postural asymmetry, characterized by an increase in flexor tonus of the ipsilateral wing and leg and an increase in extensor tonus of the contralateral limbs. This postural asymmetry was just opposite in sign to that described recently in cats, where unilateral section of the cervical dorsal roots C1-C3 produced ipsilateral hypertonia and contralateral hypotonia of the limb extensors. The striking increase in flexor tonus of the wing following deafferentation of the ipsilateral neck extensors contrasts with the decrease in flexor tonus of the wing which occurs after deafferentation of the ipsilateral leg extensors. It appears, therefore, that the proprioceptive input from the neck and that from the leg extensors exert an antagonistic influence on the flexor tonus of the ipsilateral wing.