The whiptail lizard Cnemidophorus vanzoi is a large-bodied teiid found only ontwo islands (Maria Major and Maria Minor), off St Lucia, West Indies. In May 1995, 42 lizards fromMaria Major were introduced to the smaller uninhabited Praslin Island on the same coastline. Threeyears post-release, we studied abundance, demography and morphometrics of the translocated lizardpopulation, during a 6-month period covering wet and dry seasons. Age, sex, snout–vent length(SVL), body mass (BM), tail length, tail regeneration, and overall condition (moulting, reproductivecondition, cuts, external parasites) of 107 animals caught during the study are analysed in thepresent paper. Comparisons are also made with the source population. A body condition index (CI(BM/SVL)), sex ratio (adult males : adult females), age ratio (adults : juveniles), and sexualsize dimorphism ratio (SVL adult male : SVL adult females) were calculated for the study population.Distance sampling and mark–re-sight surveys were used to estimate population size and lizarddensity. A total of 155 ± 26 individuals were estimated. The lizard population was found tohave a high growth rate (r = 0.97–3.95). There were significant seasonal changes inlizard abundance. Seasonal differences in lizard numbers, BM and CI suggest either severe resourcelimitation during the dry season, or selective aestivation. A high frequency of tail autotomy maypoint to intense intraspecific competition as the island is relatively free from main predators suchas the black rat Rattus rattus. Sex ratio, sexual size dimorphism and sexual dichromatism allindicate a territorial species in a generally non-territorial family (Teiidae). Some adult males seemto maintain juvenile colours. It is suggested that the introduced population has successfullycolonized its new environment and that no significant change in the animals condition or size hasoccurred during the 3 years since translocation.