In this study, a questionnaire was given to the caretakers of 86 riding horses to assess their impressions of the horses’ temperaments. Based on the temperament scores three factors were named to describe the data: ‘anxiety’, ‘novelty seeking’ and ‘understanding’. The same horses were subjected to a balloon reactivity test. Each horse was placed in a novel arena where its reaction to two balloons that were suspended from the ceiling and rotated was recorded. The horse’s behaviour and heart rate were recorded for the 5-minute test period. When the results of the questionnaire and the results of the reactivity test were compared, it was found that the horses that were labelled as anxious by the caretakers also had higher heart rates and defecated more during the test. Horses that were assessed as having problems with ordinary care and/or training also had increased heart rate and defecation during the balloon test. The temperament determined based on the questionnaire was highly consistent with the results of the balloon reactivity test. Based on these results, it appears that the temperament of the horse could accurately be assessed using a questionnaire survey.