An investigation is made of the anisotropic dielectric response function of quantum wells as a function of well width. We have calculated the Fresnel coefficient of reflection from such a structure taking into account the polar nature of the valence band Bloch states. The polarization dependence of the oscillator strength and resonant frequency is discussed. For the interband optical transitions, we used a two-band model to calculate the exciton wavefunction. The oscillator strength and resonant frequency is strongly affected by the direction of the incident fields because the heavy and light holes are polarized in different directions. When the electric field is along the growth direction of the quantum wells, the Fresnel coefficient contains no optical transitions of s-like heavy hole due to the optical selection rules. The dielectric anisotropy results in a renormalization of the exciton oscillator strength and for light holes gives an additional resonant energy in the reflection. Numerical results for the differential reflectivity in GaAsGaAlAs quantum wells for some typical well width are presented. © 1989.