Raman intensity analysis of LaCl₃ on lines adopted earlier for crystals like LiNO₃, KNO₃ or YVO₄ is found to be unsuitable for LaCl₃. The rotation of the LaCl₃ pyramids in the unit cell of this crystal is represented by high frequencies, comparable to the internal oscillations of LaCl₃ molecule. The intensity ofR_z, rotation about the symmetry axis of the crystal, is higher than the total symmetric line. These two factors show that the two molecules in the unit cell cannot be treated separately. Also, the polarisability of the bonds between atoms connecting the molecules cannot be neglected. The intensity formulae have been derived for this crystal and using the directional Raman spectra, electro-optical constants of the LaCl and Cl-Cl bonds have been evaluated. It is found that while the polarisability of Cl-Cl bond between the molecules, is about 0·4 times that of LaCl bonds, in crystals like LiNO₃ the polarisability of bonds like Li-O is found to be negligible.