We present comparative calculations of the electronic structure of Cd and Zn based group II-VI compounds and their heterostructures based on the density functional and tight binding theories. The First principles density functional theory (DFT) uses the modified Becke-Johnson exchange potential with LDA correlation potential (MBJLDA) and the semiempirical tight binding theory uses the first nearest neighbor (NN) sp(3)d(5) and second nearest neighbor (2NN) sp(3)s* basis with spin-orbit coupling of II cation (Cd, Zn) and VI anion (S, Se, Te) atoms for calculating the electronic structure of Cd and Zn based II-VI compounds and their heterostructures. The results of DFT with MBJLDA functional and NN sp3d5 and 2NN sp3s* TB models are found to be in excellent agreement with measured band gaps of CdX and ZnX (X=S, Se, Te) based group II-VI compounds and their CdZnS/ CdS, CdSTe/CdTe and ZnSSe/ZnSe heterostructures. We conclude that the NN sp3d5 TB model gives much more physical insight than the (2NN) sp(3)s* TB model, making use of the fictitious s* state unnecessary. 2013 Elsevier Ltd. All rights reserved.