To reveal more clearly the places that are critical for generating and sustaining species diversity, the distribution of genetic diversity is informative for conservation. Evolutionary significant units (ESUs) represent distinct lineages within a species and are defined by genetic and morphological differences. We examine morpho- metrics and mitochondrial DNA sequences of two coastal and three Andean populations of Gray-breasted Wood Wrens (Henicorhina leucophrys) in Ecuador to determine if any populations are ESUs. Coastal Wood Wrens diverged genetically by 2.4%, 3.5%, and 4.4% from Andean populations of the northwest (Bellavista), southwest (Sural- Caucha), and southeast (Romerillos), respectively. The five populations (34 individuals) exhibited nine haplotypes. Both genetic and ecological results indicate that coastal Wood Wrens found in the Colonche Hills are ESUs, as are the Andean populations. In contrast with temperate regions, where large reserves connected by corridors may be effective, preservation of biodiversity in tropical South America may require protection of more localized areas. SINOPSIS. Haplotipos en el ADN mitocondrial, divergencia en su secuencia y variaci´ on morfol´ ogica en Henichorina leucophrys, e implicaciones para la consevaci´ on