The results of study of structural genesis of the nonoriented nematic MBBA at different temperature pre-history are reported. The temperature dependent transformations of the vibrational Raman spectra and their connection with the change of MBBA structure were investigated in the spectral region 1100–1600 cm−1and in the temperature interval 163–333 K. The method to be used allows to prognosticate the structural evolution of MBBA and to identify its phase states. In particular it is found that the several coexisting fractions of different conformers may be obtained in the temperature region lower the glass transition temperature in dependence on the sample cooling rate.