A repetitive DNA element from the genome of the cestode Echinococcus granulosus has been cloned and sequenced. The 186-base-pair repeating units are arranged in direct tandem, probably clustered in the parasite genome. The estimated copy number of the repeat is 11,500 and represents between 2 and 3% of the parasite genome. The repetitive sequence is specific for Echinococcus since it does not cross-hybridize with either DNA of other cestode species or pig and dog DNA. The repetitive element is capable of detecting between 250 and 500 pg of E. granulosus DNA by dot blot assay.