The modified Forssell's procedure was performed on 10 horses in an attempt to cure oral stereotypies. Three horses were cured completely, two horses were considerably improved, and five horses continued to perform the stereotypy after periods of remission ranging from two weeks to six months. This rate of success for the modified Forssell's procedure, as in other published reports, was lower than for the original Forssell's procedure. Surgery to eliminate a stereotypical behaviour pattern may exacerbate the stress for an animal and the modified Forssell's procedure can no longer be recommended for the treatment of oral stereotypies in horses.