The aim of this thesis is to determine the horse's gait types using the acceleration values measured from the horse. Measurements were taken at a race track in Gävle, Sweden. A total of five Nanotrak sensors were used, four on the different parts of the horse, and one on the hand of the horse's driver; a car was driven parallel to the horse and the motions of the horse was recorded by a camera in order to synchronize with the data measured by the sensors. In total four sets of measurements were recorded. The software to process the data was Matlab, and the main mathematical tool to analyze it was Short Time Fourier Transform (STFT), different windows were evaluated as well as the data length. The method for classification of horse's gaits was categorized as amplitude of the fundamental frequency component. The method shows promising results with a misclassification below one percent. However, higher sampling rate, more measurements and more analysis are needed to be done in the future to find a proper way to automatic determine the horse's gaits.