We observed that the superconducting critical temperatureTc(x) of the oxides (R1−xPrx)Ba2Cu3O7−y(R=Er, Y, Dy, Gd, Eu) decreases monotonically with increasing Pr concentrationx. Using the reduced parametersTc/Tc(0) andx/xcrall the experimental data for five studied systems fall onto the theoretical universal curve of Abrikosov and Gor’kov over the reduced Pr concentration regime,x/xcr<0.6, wherexcris the critical concentration of Pr for the complete suppression of superconductivity andTc(0) is theTcfor undoped material. The consistency of these results suggests a pair‐breaking mechanism which plays a role in depressing superconductivity in these highTcoxides.