The magnetic hyperfine field (Bhf) in RZn compounds (R = Gd, Tb, Dy) has been investigated by perturbed angular correlation spectroscopy using 140Ce and 111Cd as probe nuclei, respectively, at R and Zn sites, in order to study the origin of the magnetic coupling in these compounds. The results for 111Cd probe showed that the temperature dependence of Bhf roughly follows the Brillouin function for the R total angular momentum J of each compound. The temperature dependence of Bhf measured with 140Ce probes showed, however, a sharp deviation from the Brillouin curve for all compounds, which was ascribed to the contribution of the 4f-electron of Ce3+ to Bhf.