The aim of the study was to determine the first reaction of the heart rate (HR) in horses to piping music of different genres into the stable for a short time. The study included 26 saddle horses, mares, stallions and geldings, split into three age groups: 1-5, 6-11 and over 11 years. Three kinds of music were played within three 25-minute tests conducted on three successive days, one test a day. The tests differed in the sequence of music genres: rock, country and relaxing music. The analysis considered the mean HR at rest and during the first two and three minutes of the whole sequence of the three music genres, as well as during particular genres: minimum and maximum HR, difference between maximum HR and HR at rest, as well as the time in which HR decreased from the maximum level to the level before music was played. The data were verified by T-Tukey’s test and by ANOVA (GLM) with regard to sex, age group and music test factors. The results show that music played at 80 dB caused a short HR elevation. The level of emotional excitability measured by HR was different for the three music genres. The relaxation music had the mildest effect, the country music acted more strongly, and the influence of the rock music was the strongest. This finding is based on the mean HR for the first two minutes of a music test, extreme HR, difference between maximum HR and HR at rest, as well as the time in which HR decreased from the maximum level to the level before music was played. Differences in reactions of the horses to music were related to their sex and, to a smaller degree, their age.