Combinations of romifidine and butorphanol were used to sedate 55 horses for a variety of surgical, therapeutic and diagnostic procedures. Eighteen of the horses were given the drugs separately, romifidine first followed by butorphanol four minutes later, and 37 were given the drugs together. The levels of sedation and ataxia were assessed and graded, and there were no statistically significant differences between the two methods of administration. The side effects were typical of the alpha-2 agonists, including bradycardia, heart block and some sweating. Box-walking was observed in one horse. The procedure attempted was successfully completed in 54 of the horses, and the combination of drugs was judged to be a safe and effective sedative for horses.