A short interspersed nucleotide (nt) element ( SINE) was cloned from the genomic DNA of the domestic dog, Canis familiaris. Southern-blot analysis of canine DNA digested with four restriction endonucleases indicated that the SINE is widely dispersed throughout the genome. Hybridization also indicated that the element may be unique to canids and is absent in a variety of other mammals, including members of four closely-related carnivore families. Three examples of the SINE have been located and sequenced. The 130-bp SINE contains putative RNA polymerase III transcriptional control sequences. The SINE is flanked at the 3′ end by a (TC) 8-repeat region followed by a poly(A) tract of 35–65 nt. Computer database searches located two homologous sequences with approx. 80% identity to the SINE. These sequences were located in untranslated regions of the canine genes encoding interferon-ω and clotting factor IX.