This study used ISSR markers to assess the genetic diversity of a collection of 15 genotypes of Salix purpurea and 6 interspecific hybrids, employing 40 of 60 tested ISSR primers generating polymorphic amplification products. The PCR-ISSR method was adapted for S. purpurea by optimizing the annealing temperature for each primer. The polymorphism index of ISSR amplification products was 91.8% for all studied genotypes and 70.4% for S. purpurea genotypes. Nei's genetic identity statistics ranged from 0.538 to 0.958. Nei's genetic distance values were used to build a dendrogram (UPGMA) for the investigated genotypes. The dendrogram shows five clusters, and principal coordinate analysis yielded nearly the same genetic relationships among the studied genotypes. The results confirm the usefulness of ISSR markers for determining genetic diversity in S. purpurea.