Two‐photon absorption in GaAs/Ga1−xAlxAs with a realistic band structure and finite band offsets &Dgr;Ec, &Dgr;Evis analyzed theoretically and compared with experiment. This approach allows us to explain the known experimental data and choose the most realistic value for the ratio &Dgr;Ec/&Dgr;Ev. It is shown that for thin quantum wells the number of possible two‐photon optical transitions in the well decreases which strongly affects the polarization dependence of two‐photon absorption in GaAs/Ga1−xAlxAs heterostructures. ©1996 American Institute of Physics.