  We study the spin-spin and energy-energy correlation functions for the 2D
Ising and 3-states Potts model with random bonds at the critical point. The
procedure employed is the renormalisation group approach of the perturbation
series around the conformal field theories representing the pure models. For
the Ising model, we obtain a crossover in the amplitude for the correlation
functions which doesn't change the critical exponent. For the $3$-state Potts
model, we found a shift in the critical exponent produced by randomness. A
comparison with numerical data is discussed briefly.
