The product operator descriptions of INEPT and reverse INEPT (RINEPT) NMR experiments are introduced for weakly coupled ISn (I = 1/2, S = 3/2 with n = 1, 2, 3) spin systems. Explicit expressions for polarization transfer from spin-3/2 quadrupolar nuclei to spin-1/2 nuclei (and reversed polarization transfer) are given in detail by using the evolutions of product operators under the spin-spin coupling Hamiltonian. The results calculated for the intensities and positions of the observable signals are simulated in the molecules containning the Sn-119 (I = 1/2) and Cl-35 (S = 3/2) nuclei at the coupling constant of J(Sn-Cl) = 375 Hz by using the Maple programme on computer. (C) 2004 Elsevier Inc. All rights reserved.