Fetal development of the central nervous system is an important and sensitive stage which is affected by many external and internal stimuli. This study aimed to investigate effect of musical stimuli on fetal rat brain. In this experimental study, twelve female Wistar rats were selected and evenly assigned to control and musical groups. The females were mated with a male rat of the same genotype. Musical group was exposed to classic music with 60 dB power for 90 minutes twice per day from 2 [nd] to 20 [th] day of gestation. The control rats were handled similar to the musical group, but were not exposed to music. Before parturition, all the dams were anesthetized, and their blood samples were obtained and used for corticosterone [COS] measurement. They were transcardially perfused by electron microscope [EM] fixative agent. The fetal brains were extracted intact and used for slice preparation. Horizontal slices were made for electron microscope preparation, and images were taken and analyzed in terms of cell density and morphological changes. EM observation indicated significant morphological difference in cellular and intercellular spaces between the two groups. Music-treated fetuses had significantly higher cell density in parietal cortex and music-treated dams had lower COS level. It was concluded that prenatal music would have a great impact on neuroplasticity of fetal rat brain, at least indirectly. Although the rat fetuses cannot hear until birth, music-induced reduction in COS blood level of dams might be the reason for neuroplasticity of fetal brain