The invention concerns a process and a facility for reducing the concentration of heavy polycyclic aromatic compounds (HPNA) in the recycle loop of hydrocracking units, which comprises a fractionation column.In accordance with this process, a stream is withdrawn from the fractionation column at the level of at least one plate located between the supply plate and the plate for withdrawing the heaviest distillate fraction; the stream is stripped in an external stripping step by a stripping gas, in the presence of a portion of the residue. The separated gaseous effluent is recycled to the column, advantageously as a stripping gas, and the liquid fraction is recycled to the hydrocracking step; a residue is purged in the stripping step.