Studies on mammalian fauna from the Andaman & Nicobar Islands have been done by various researchers but meager information is available on rodent fauna from these Islands.  Morphometric and cranial details of fresh specimens of one of the rodent species, Rattus andamanensis (Blyth, 1860) of family Muridae, collected from its type locality in southern Andamans has been reported in the present paper.  Morphological variations within the population are discussed.  Observations on in-captivity-development of the young ones of the species in the laboratory are also recorded.