A 7-year-old Thoroughbred racehorse developed loud exercise-related respiratory noises and exercise intolerance over a short period. Examination showed congenital cricopharyngeal-laryngeal dysplasia (rostral displacement of the palatopharyngeal arch) and also left sided idiopathic laryngeal hemiparesis, the latter appearing to be of recent clinical onset. The animal developed colic some months after laryngeal surgery and a nephrosplenic entrapment was surgically corrected. Aerophagia and regurgitation worsened after surgery and, after developing inhalation pneumonia, the animal was destroyed. Post-mortem examination confirmed the presence of idiopathic laryngeal hemiparesis and of cricopharyngeal-laryngeal dysplasia which had some previously undescribed laryngeal muscle abnormalities.