Full-length mariner elements were isolated and sequenced from house flies (Musca domestica) and German cockroaches (Blattella germanica). The amino acid sequence of the house fly mariner element (accession number: AF373028) showed 99.5% identity with Mos1 and peach elements, whereas the German cockroach mariner element (accession number: AF355143) showed 98.8% and 99.8% identity, respectively. Sequence analysis revealed that the mariner elements in house flies and German cockroaches differed from the active Mos1 mariner element by seven and 15 nucleotides, respectively. Four essential nucleotide substitutions at positions 64, 154, 305, and 1203, which have been proposed to contribute to the loss of activity of the inactive elements, were detected in the German cockroach mariner element. In contrast, although the mariner element in house flies contained substitutions at positions 64, 154, and 305, it retained T at position 1203, identical to active mariner elements. Mariner is present in approximately eight copies in the German cockroach genome.