We studied cross nuclear and mitochondrial gene pools of brown hares (Lepus europaeus) from three Local populations in Britain and two in New Zealand, to test the hypothesis of reduced genetic variability in hares from New Zealand resulting from few founders originating from Britain. Multilocus allozyme electrophoresis of 52 protein Loci and analysis of restriction fragment length polymorphisms of total mitochondrial DNA based on 16 hexanucleotid-cleaving restriction enzymes were employed in 119 and 36 hares, respectively. Observed and expected average heterozygosities, rates of polymorphism, average numbers of alleles per Locus, Shannon-Weaver information indices of allelic diversity, as well as values of haplotype and nucleotide diversity were similar in all regional samples. But hares from both New Zealand and Britain had significantly lower genetic diversity than brown hares from continental Europe studied earlier. Thus, gene pool erosion Likely occurred already in British hares, perhaps associated with their probable introduction in Roman times. Theoretically, the small number of alleles found in British brown hares could have been sampled by the few hares that were reported as having constituted the founder stock in New Zealand in the nineteenth century. As expected, rare alleles of British brown hares were absent in New Zealand, But drift had only a slight effect on the gene pool composition of hares in New Zealand.