We have carried out the molecular characterization of a highly repeated DNA element, called E12, from Trypanosoma cruzi, which has been found to be interspersed along its genome. The E12 element, repeated about 5.6 x 10(3) times, is found in most of the chromosomal bands of the parasite. Three subregions may be defined within the element on the basis of sequence similarities with other trypanosome genomic sequences. Northern blot analysis demonstrated that sequences of the E12 element are present in several polyadenylated RNA species of T. cruzi. The isolation and characterization of a cDNA clone, pSPFM55, which showed hybridization with the E12 probe, indicated that only one of the E12 subregions, E12A, is found in the cDNA and that it is located at the 3'-end providing the site of polyadenylation addition. The location and high degree of nucleotide conservation of E12A suggest a possible functional role of this sequence in gene expression.