  We have studied the solubility of molecular hydrogen in bulk liquid $^4$He at
zero temperature using the diffusion Monte Carlo method and realistic
interatomic potentials between the different species of the mixture. Around the
$^4$He equilibrium density, the H_2 molecules clusterize in liquid-like drops
blocking the existence of a uniform dilution. On the contrary, at higher
densities the cluster formation is less feasible and metastable dilute
solutions may exist.
