The most common causes of gastrointestinal colic at an equine referral hospital in South Africa were determined following retrieval of the medical records of horses admitted during a 10-year study period. The study included 935 horses of which 28 % were admitted after hours. Most horses were Thoroughbreds (54 %), male (57 %), with a mean age of 8.2 years and originated from the Gauteng Province (81 %). Heart rate (98 %), mucous membrane colour (95 %) and auscultation of the abdomen (91 %) were the clinical data commonly obtained at admission. Packed cell volume, total serum protein and white cell count were recorded in 78 %, 75 % and 44 % of horses respectively. Transrectal palpation (93 %), nasogastric intubation (84 %), intravenous catheterisation (74 %) and abdominocentesis (53 %) were the most frequently performed procedures. Medical intervention was performed in 558 horses (60 %). The common causes of medical colic were impactions (39 %), tympany (7 %) and displacement of the large colon (6 %). An exploratory laparotomy was performed in 331 horses (36 %). The common causes of surgical colic were displacement (29 %), impaction (22 %) and small intestinal strangulating lesions (18 %). Death occurred in 3 % of horses, while euthanasia before medical intervention was performed in 4 %. Overall, medical intervention was successful in 93 % of horses and 67 % in horses managed surgically. In conclusion, 55 % of all the equine admissions responded to medical intervention and the recovery rate for horses receiving both medical and surgical intervention was comparable to that reported in other studies.