Swiss and Spanish isolates of Echinococcus granulosus were compared using different molecular biological techniques: Genomic DNAs isolated from parasites originating from various intermediate hosts were subjected to Southern hybridization with different probes, the same source of DNA was used for DNA amplification using the Random Amplified Polymorphic DNA (RAPD) technique. With both methods the various isolates (metacestodes) of E. granulosus exhibited characteristic banding patterns which allowed us to assign them to the following groups of homologous profiles: (a) isolates of horse and donkey origin from Spain and Switzerland; (b) isolates of cattle origin from Switzerland; (c) isolates of sheep, cattle and human origin from Spain; (d) isolates of pig origin from Spain and Switzerland and of goat origin from Spain. By RAPD (Southern hybridization not examined) two isolates of human origin from Switzerland were showing banding patterns distinct from groups (a-d). The results provide further evidence that the morphological and biological differences of several strains of E. granulosus are also detectable on the genetic level using molecular biological techniques.