Semi-leptonic decays of heavy mesons

We present results of a lattice computation of the matrix elements of the vector currents which are relevant for the semileptonic decays of D to K, D to pi and B to pi. The computations are performed in the quenched approximation on a 24^3x48 lattice at beta=6.2, using an O(a) non-perturbatively improved fermionic action.