Background:Studies in Chilean adults of low socioeconomic level suggest that their low height is likely to be due to their indigenous background. However this group also has been marginalized from socioeconomic development. Aim: To determine the influence of Mapuche ethnic origin and socioeconomic factors on the height of adults. Subjects and methods: In a cross sectional design, the height of 1,293 adults (528 males and 765 females) of Mapuche and non Mapuche origin were studied in the Araucania Region (Southern Chile) and in the Metropolitan Region (Central Chile). Subjects with Mapuche surnames were considered as pertaining to this ethnic community and those with Spanish surnames were considered as non Mapuche. Linear regression models were done, stratifying by sex, considering ethnic origin, to live in counties of different social vulnerability, and the level of family poverty. Results: Among males, the mean height was 166.6±7.3 cm and among females, the figure was 153.6±5.9 cm. Mapuche subjects were significantly shorter: -3.2 cm (95% Confidence Interval (CI) -4.0 to -2.3) among females and -4.8 cm (CI -6.0 to -3.6) among males (non adjusted models). This deficit increased to -4.5 and -7.6 cm among females and males, respectively when they lived in poverty and in areas with highest social vulnerability. These differences decreased significantly if Mapuche subjects lived in communities with low social vulnerability and less poverty (-0.59 and -1.14 cm among females and males respectively). Conclusions: The studied population had low height, being lower in Mapuche subjects. The differences decreased among subjects living in counties of less vulnerability and less family poverty