  We show how to perform a resummation, to all orders in perturbation theory,
of a certain class of gauge invariant tadpole-like diagrams in Lattice QCD.
These diagrams are often largely responsible for lattice artifacts.
  Our resummation leads to an improved perturbative expansion. Applied to a
number of cases of interest, e.g. the lattice renormalization of some
two-fermion operators, this expansion yields results remarkably close to
corresponding nonperturbative estimates.
  We consider in our study both the Wilson and the clover action for fermions.
