White-tailed Deer, Odocoileus virginianus, the common deer of eastern North America, currently number approximately 2-3000 on Nantucket Island. Although white-tailed deer remains are known from Wampanoag archeological sites on the island, no deer were noted by the beginning of the 20th century. Most accounts of the history of deer on Nantucket say that in 1922 a single male deer was found swimming in Nantucket sound and brought ashore by a local fisherman. In 1926, 2 female deer from Michigan were imported to the island as companions for the lone male. This scenario implies that the thousands of deer on Nantucket are descended from these three original animals. From this start, the deer herd grew to several hundred by 1935. However, historical records also indicate that additional deer (2 males and 3 females) were brought to the island from New Hampshire in 1935 and 1936. My research students and I have been looking at patterns of genetic variation in deer from Nantucket, surrounding mainland areas, as well as Michigan. Using mitochondrial DNA sequence variation, which tracks maternal inheritance, preliminary results support the hypothesis that most of the deer on Nantucket are descendants of deer from Michigan. There is also evidence that some of the deer on the island are from ancestors on the New England mainland. As predicted from the known history of the herd, genetic variation among deer on Nantucket is much lower than in deer herds on the mainland of Massachusetts.