In the majority of the species studied to date, males have more advanced visual-spatial capabilities. The sex differences in the visual-spatial abilities of horses are yet to be determined. The visual-spatial abilities of male and female horses were assessed during a series of six tests involving a novel test apparatus. The test apparatus contained four adjoining stalls. Each stall contained a feed bin and a moveable barrier, and the barrier controlled and limited the access that the horses had to the feed bin, except in one stall. Males completed each of the six tests significantly faster and made fewer errors than the female horses. The male horses also complete significantly more of the tests than the females. The males horsed took significantly longer to complete the first task than tasks two to five. This difference was not found in the female horses. Thus, based upon the behaviour of the horses in the tests, the males demonstrated that they have much more acute visual-spatial abilities than female horses, which is similar to the findings of other species.