Seventeen haplotypes were detected from the complete mitochondrial DNA control region sequences analyzed from eighty individuals of two Tibetan domestic sheep breeds. The nucleotide composition of all the sequences was 33.0% A, 29.7%T, 22.9%C and 14.4%G; G+C was 37.3%. The length of the sequences ranged from 1,107 bp to 1,259 bp. The difference between them was primarily due to 3-5 copy numbers of a 75 bp tandem repeat sequence. The NJ phylogenetic tree (the number of replications of bootstrap test is 1,000) presented three major domestic sheep lineages, which suggested that modern Tibetan sheep breeds are derived from three maternal sources.