Morphological variation, the karyotype, and reproduction in the parthenogenetic blind snake (Ramphotyphlops braminus) were studied on the basis of a large sample from the Ryukyu Archipelago, Taiwan, and Saipan. Meristic and morphometric characters showed little geographic variation. The numbers of transverse scale rings and vertebrae, each somewhat variable within the sample, were significantly correlated with each other. The karyotype of specimens from the Ryukyu Archipelago and Taiwan consists of 42 chromosomes best interpreted as forming 14 triplets, indicating that R. braminus from this region has a triploid karyotype. Clutch size varied from one to eight, and was significantly correlated with the snout-vent length. From observations of gonads in preserved specimens and from captive breedings, R. braminus begins reproduction after April in the Ryukyu region.