Introduction. Little evidence is available concerning the morphological modifications of motor cortex neurons associated with peripheral nerve injuries, and the consequences of those injuries on postlesion functional recovery.Objective. Dendritic branching of cortico-facial neurons was characterized with respect to the effects of irreversible facial nerve injury.Materials and methods. Twenty-four adult male rats were distributed into four groups: sham (no lesion surgery), and dendritic assessment at 1, 3 and 5 weeks post surgery. Eighteen lesion animals underwent surgical transection of the mandibular and buccal branches of the facial nerve. Dendritic branching was examined by contralateral primary motor cortex slices stained with the Golgi-Cox technique. Layer V pyramidal (cortico-facial) neurons from sham and injured animals were reconstructed and their dendritic branching was compared using Sholl analysis.Results. Animals with facial nerve lesions displayed persistent vibrissal paralysis throughout the fiveweek observation period. Compared with control animal neurons, cortico-facial pyramidal neuronsof surgically injured animals displayed shrinkage of their dendritic branches at statistically significant levels. This shrinkage persisted for at least five weeks after facial nerve injury.Discussion. Irreversible facial motoneuron axonal damage induced persistent dendritic arborization shrinkage in contralateral cortico-facial neurons. This morphological reorganization may be thephysiological basis of functional sequelae observed in peripheral facial palsy patients.