Objectives Reference intervals (RI) are an essential tool to support clinical decisions. These may have intra- and inter-individual variations associated with genetic differences and environmental factors. Given that Chile is a multiethnic territory, studying these variables is even more relevant. The purpose of this study was to establish RI for various hematological parameters in the Chilean population and the Mapuche ethnic group. Methods A sample of 356 adult individuals (aged 18-65 years), of which 146 belonged to the Mapuche ethnic group, was selected using the indirect a posteriori method from the database of the UC Temuco Clinical Laboratory. The analysis was conducted by sex and ethnicity. The Tukey fences method was employed to detect outliers, and the RIs were established through the non-parametric method recommended by the IFCC. Results The median age for the overall sample of the general population was 35 years (female) and 36 years (male). Differences (p<0.05) were found by sex in parameters dependent on hemoglobin and platelets counts. In the analysis by ethnicity, the parameters of RBC, HGB and HCT presented significant differences (p<0.0001). Conclusions This study shows that hematological RI vary according to sex and ethnicity, which must be considered in a multiethnic population. This understanding enhances our comprehension of the individual characteristics of each person and facilitates more accurate clinical interpretation.