The pressure effect of the superconducting transition temperature T-c for t
he series of (R1-xPrx)Ba2Cu3O7 with R = Yb, Dy and Nd are examined. Our res
ults prompt us to believe that the origin of T-c-suppression by Pr-doping i
n (R1-xPrx)Ba2Cu3O7 is objective to the ionic size of R.