Thirty million Americans ride horses; 50,000 of these riders are treated in emergency rooms annually. Equestrian activities are uniquely dangerous because the participant is unrestrained, often helmetless, and riding large, unpredictable animals capable of 40-mph speeds and kicking with up to 1 ton of force. Neurologic injuries in equestrians constitute the majority of severe injuries and fatalities. We prospectively studied all patients admitted to the University of Kentucky Medical Center with equine-related neurosurgical trauma from July 1992 to January 1996. Eighteen of 30 patients were male. Age ranged from 3 to 64 years. Five patients died (17%), and two suffered permanent paralysis. There were 24 head injuries (80%) and 9 spinal injuries (30%). The majority of injuries (60%) were caused by ejection or fall from the horse. Twelve patients (40%) were kicked by a horse, and four patients sustained crush injuries. Six patients underwent craniotomy, three had operative spinal stabilization, and five required ventriculostomy. Eleven patients (37%) were professional riders. Twenty-four patients (80%) were not wearing helmets, including all fatalities and craniotomy patients. Our data show that equine-related neurosurgical injuries can be severe and fatal because of the significant size, force, and unpredictability of these animals as well as the lack of proper headgear. We recommend that helmets be worn at all times around horses because a significant number of our patients (33%) were injured as bystanders. Risk of serious injury appears to be a function of cumulative exposure to horses, not level of expertise. Experience is not protective; helmets are.