Collections of old scales from salmonid fishes can be found in many fisheries institutions in Europe and North America. Such scales have been shown to be useful as a source of DNA, which can be used for analysis of microsatellites. We here describe the technical procedures in relation to extraction and PCR amplification of DNA from old scales. Further, we describe case stories of the application of old scale DNA analysis for conservation genetics with regard to: 1) Identification of native populations, 2) assessment of loss of genetic variation, 3) estimation of effective population size, 4) evaluation of anthropogenic effects on the genetic population structure/mode of migration and 5) the temporal stability of the genetic population structure. Finally, we describe the perspectives for future genetic studies using old scale DNA. In particular, we evaluate other types of genetic markers such as mtDNA and loci subjected to selection, in association with old scale DNA, as tools for prioritising populations for conservation.