The Fourier-transform Raman spectrum of natural rubber is presented as a function of time of cold soaking at -25 degrees C and of strain with respect to laser polarization. Under both sets of conditions, changes occur in the spectra that can be attributed to crystallization. Difference spectra showing only those bands due to crystallization (i.e, spectra of crystalline natural rubber) are presented, which allows the crystallization process to be discussed with respect to the conditions under which crystallites are formed. A combination of Fourier-transform Raman and Fourier-transform infra-red depolarization spectra has been used to deduce preliminary assignments for some of the vibrational bands of natural rubber.