In the present study we review datasets available for the Chilean margin to assess the relationship between environmental (or habitat) heterogeneity and benthic diversity. Several factors, such as the presence of different water masses, including the oxygen-deficient Equatorial Sub-surface Waters (ESSW) at the continental shelf and upper slope, and the Antarctic Intermediate Waters (AIW) at mid slope depths appear to control the bathymetric distribution of benthic communities. The presence of methane seeps and an extended oxygen minimum zone (OMZ) add complexity to the benthic distribution patterns observed. All these factors generate environmental heterogeneity, which is predicted to affect the diversity patterns both along and across the Chilean continental margin. The response to these factors differs among different faunal size groups: meio-, macro-, and megafauna. Physiological adaptations to oxygen deficiency and constraints related to body size of each group seem to explain the larger-scale patterns observed, while sediment/habitat heterogeneity (e.g. at water mass boundaries, hardgrounds, biogeochemical patchiness, sediment organic content, grain size) may influence the local fauna diversity patterns.We thank the Census of Marine Life and affiliated field project COMARGE, in particular Drs Lisa Levin, Myriam Sibuet, Lenaick Menot, Craig Smith, Ann Vanreusel and Andrew Gooday, who organized the workshop 'Roles of Habitat Heterogeneity in generating and maintaining Continental Margin Biodiversity', held at Scripps Institution of Oceanography, CA, USA. We are also indebted to the participants of the R/V Sonne (SO-156, PUCK expedition 2001), especially Drs Wolf Arntz, Victor A. Gallardo, Dieter Gerdes and Dierk Hebbeln. The expedition was funded by the German BMBF (grant No. 03GO156A). We also thank the captain and crew of the Chilean Navy's R/V Vidal Gormaz for support at sea during the SeepOx cruise, funded by FONDECYT project #1061217 to J.S. The comments and suggestions of three anonymous reviewers greatly helped to improve this manuscript. The COPAS (Universidad de Concepcion) and CIEP (Gobierno Regional de Aysen) centers are thanked for support to J.S. and E.Q., respectively, during the writing phase of this work.24FONDEFsellanes@ucn.clGerman BMBF [03GO156A]; FONDECYT [1061217]1FONDEF31