Objective To evaluate the effects of music in dairy cattle as a function of leukocyte population and voluntary entry into the milking parlor to reduce animal stress. Methods The hypothesis to be tested is that the application of music to dairy cattle produces a significant change in the leukocyte counts and voluntary entry into the milking room and trap. An experimental design ABAB was employed, consisting of sessions with and without music within the milking system and management traps of 15 Holstein cattle over a 14-day period. At the end of each period, blood samples were taken for leukocyte analysis. To evaluate the behavior, their voluntary progress to the management traps and milking system was timed. The Wilcoxon signed-rank test was performed for related samples with a 95% confidence interval. Results When music was played, dairy cattle voluntarily approached the milking system and traps (A1B1 and A2B2, p = 0.000). At the same time, the leukogram showed a significant difference in total leukocyte (P < 0.05) due to increase in lymphocyte concentration. Conclusion The hypothesis was verified: the use of music in dairy cattle produces a significant effect on the tested variables.