General relations satisfied by scattering matrices, matching matrices for coefficients, transfer matrices, and matching matrices for envelope functions are derived for systems with heteroboundaries. It is shown that the relations found for these matrices are fulfilled to good accuracy within the models proposed for the GaAs/AlAs(001) heterostructure.At present, the scattering matrix method has gained acceptance for solving various quantum-mechanical problems for systems with heteroboundaries. To calculate matrix elements of the scattering matrix S(N), where N is the number of heteroboundaries, various approximations are used. To verify these approximations, we should have exact relations the matrix must satisfy. Note that the well-known unitarity conditions for the scattering matrix proper are insufficient for verification, because in this case, the relations are obtained only for a small number of matrix elements composing the complete scattering matrix. Recall that a matrix formed from the matrix elements of the complete scattering matrix S(N) corresponding to the propagating (non-decaying at infinity) states is referred to as the scattering matrix proper [1].Various problems for systems with heteroboundaries can be solved using the transfer matrix method. For finding both the transfer t(n) and scattering S(N) matrices, use is made of the matching matrices for coefficients I(n) calculated using different models and approximations. Therefore, to verify these approximations, the relations satisfied by the t(n) and I(n) matrices should be known. We note that the I(n) matrices can also be used for constructing various simplified models, for example, the envelope function model. Thus, given general relations for I(n), the relations for the envelope-function matching matrix can be found and used to verify the validity of a simplified model for the exact problem.This work is aimed at deriving general relations satisfied by the scattering matrices, matching matrices for coefficients, transfer matrices, and matching matrices for envelope functions in systems with heteroboundaries. The relations are used for verification of applied approximations by the example of the GaAs/AlAs (001) heterostructure. Recall the fundamental relations of the abrupt interface potential model [1, 2]. Let us consider a system with N heteroboundaries passing over the ( 1, 2,..., ) n z z n N = = planes. A medium n is in the 1 n n z z z − ≤ ≤ region. Some of the N+1 materials (subsystems) forming the system can be identical. To the left of the z 1 interface, there is a semi-infinite medium 1. To the right of z N+1 , there is a semi-infinite medium N+1. Within this model, a general solution to the Schrödinger equation for an arbitrary component of the heterostructure can be represented at fixed || k and energy E as ( ) ( ) ( ) , , ,