  We report ground state energies and structural properties for small helium
clusters (4He) containing an H- impurity computed by means of variational and
diffusion Monte Carlo methods. Except for 4He_2H- that has a noticeable
contribution from collinear geometries where the H- impurity lies between the
two 4He atoms, our results show that our 4He_NH- clusters have a compact 4He_N
subsystem that binds the H- impurity on its surface. The results for $N\geq 3$
can be interpreted invoking the different features of the minima of the He-He
and He-H- interaction potentials.
