A seven year old Quarter Horse mare presented to Cornell University Equine and Farm Animal's Hospital Emergency Service for a week long history of mild discomfort, and a twenty four hour history of more severe colic signs that were unresponsive to medical management in the field. Upon presentation, rectal examination revealed distension of the large colon, and ultrasound examination showed a segment of edematous colon. The decision was made to take the horse to surgery for an exploratory celiotomy because of her degree of pain and increasing abdominal distension. Three enteroliths were located in the mare's large and small colon, and were removed via enterotomy. Enterolithiasis is a common cause of colic in horses in the western United States, and abdominal radiography can be a useful diagnostic tool. Treatment is surgical removal when the enteroliths cause gastrointestinal obstruction, and prognosis is excellent if the horse is systematically healthy at the time of surgery. In this case, the patient recovered from anesthesia without complications. Post operatively the mare was inappetant and developed mild colitis that required ten days of medical management before she was discharged from the hospital.