In this work, the high frequency dielectric relaxation process has been studied for the N*, S*Aand S*Cphases of the mixture ZLI 3654. To this end, time domain spectroscopy (TDS) was used to cover the frequency range from 107to 1010Hz. The dielectric parameters obtained show that the high frequency spectrum is mostly influenced by the reorientation of molecules around their long axes. In addition, the latter process seems to be strongly hindered in the S*Cphase, because the necessary relaxation time is of the order of 1 ns, whereas for the N* and S*Aphases, the relaxation time is remarkably shorter and equal to 0.3 and 0.4 ns, respectively.