Several analytical, semiempirical models are presented for the complex dielectric function, ε(E)=ε₁(E)+iε₂(E), of crystalline semiconductors. The harmonic oscillator approximation (HOA) model successfully explains the peculiar experimental a spectra; however, the model cannot be expected a priori to provide satisfactory fits to the dependence of e on external perturbations or to the line shape of the derivatives of ε. The standard critical point (SCP) model provides satisfactory fits to the derivatives of ε, but does not yield good fits to ε. The model dielectric function (MDF), on the other hand, results in excellent agreement with experimental data both for a and its derivatives. The MDF is, thus, con-cluded to be more useful than the HOA or SCP model.