A generalized WKB method is used to obtain full wave solutions for the TE (horizontally polarized) and TM (vertically polarized) waves in multimode, inhomogeneous dielectric waveguides. The results are compared with recently published solutions based on a perturbational method and on the more familiar WKB method. Solutions based on the direct numerical integration of the differential equations for the transverse field components are also obtained to determine the validity of the different solutions. It is shown that the second-order perturbational solution provides a significant improvement to the familiar WKB solutions only for the principal mode. For the second and all the higher-order modes the WKB method yields more accurate solutions than the second-order perturbational approach. The generalized WKB solutions yield accurate solutions for the principal and the higher-order modes.