Background Neuropsychological testing is difficult in allochthonous older individuals due to language, sociocultural, and educational differences with autochthones. Using biomarkers could help making early diagnosis of neurodegeneration in this population, but so far very few studies have investigated biomarker differences between allochthones and autochthones. We aimed to characterize the Alzheimer’s disease (AD) cerebrospinal fluid (CSF) biomarkers (protein TAU, amyloid β42, tau/amyloid β42 ratio and pTau) in autochthonous and allochthonous patients. Besides ethnic origin, we matched our groups for sex and age. Method Between 2010 and 2014, patients had CSF sampling in Belgium, either at the Saint‐Luc Memory Clinic, Brussels (n=309) or at other hospitals (n=2096) which sent their CSF samples to the Saint‐Luc Neurochemistry lab. We conducted three linear regressions each predicting one CSF biomarker with demographic variables: age, sex and presumed ethnic origin. For this last variable, we categorized the patients according to their names and surnames in: autochthones and allochthones. Secondary analyses in a subset (n =346) adjusted for age and sex. Results Allochthones (65,9 +/‐ 9,0) attended the Memory clinic at a younger age than autochthones (70,5 +/‐ 9,3) (mean +/‐ SD). The Mann‐Whitney test we conducted has shown a significant difference for age (p<0,0001). The multiple regressions have pointed out the age to have a significant effect on all the biomarkers (p=0,0001), the sex a significant effect on TAU (p<0,05) and the ethnic origin on both TAU and tau/amyloid ratio (p<0,02). Adjusting for age and sex [median (interquartiles)] TAU 263 (165,5 – 508,3) for Italians, 277 (174,5 – 447,5) for Maghrebis, 207 (128,5 – 298,5) pg/ml for autochthonous), pTAU 44,5 (32 – 71) for Italians, 44 (31 – 58,5) for Maghrebis , 32 (23 – 44) pg/ml for autochthonous and the TAU/amyloid ratio 0,62 (0,31 – 1,34) for Italians, 0,54 (0,28 – 1,37) for Maghrebis, 0,32 (0,21 – 0,74) for autochthonous) were significantly ...