Exposure to high altitude leads to an increased formation of free radicals. The elevation of free radicals in Chronic Mountain Sickness suffers (CMS+) may contribute to systemic vascular dysfunction in comparison to the well-adapted controls (CMS-)1. Furthermore, increased oxidative stress is associated with ageing and age-related diseases2. In contrast, the protective role of antioxidants (ascorbate, tocopherols and carotenoids) in minimising oxidative stress has been well documented3. Hence, the aim of this study is to investigate the intake of dietary antioxidants in at-risk groups. Thirty-six male highlanders with CMS (n=22, CMS+; age 57±10), without CMS (n=14, CMS; age 52±12) and twenty-eight male aged lowlanders (n=28; 67±6) consented to the study. Participants were interviewed to collect a 24-hour structured dietary recall using a portion size photo atlas4. The stages followed in the UK Low Income Diet and Nutrition survey were used5. Dietary data were analysed using NetWISP dietary analysis software (Version 4.0, Tinuviel Software; Anglesey, UK). Data were tested for normality using Shapiro-W-Wilks tests. Kruskal-Wallis and Mann-Whitney tests to compare the groups were performed. Significance level was established at P<0.05 and data are expressed as mean ± standard deviation (SD).Consumption of ascorbate (vitamin C) and carotene were deficient in the chronic mountain sickness patients (CMS+) versus the well-adapted controls (CMS-) and aged lowlanders (table). Vitamin E (α-tocopherol) was also deficient in the maladapted and well-adapted highlanders in comparison to the aged lowlanders as shown in table 1. The intake demonstrates the (borderline) significant difference between CMS+ and CMS- (P<0.08) for ascorbate and carotene and significant difference with the aged lowlanders (P<0.05) for vitamin C; while no significant difference was observed for carotene. Consumption of Vitamin E is deficient in both highlander groups vs. aged lowlanders (P<0.05). The findings support the hypothesis that diseased native highlanders have an inadequate intake of dietary antioxidants compared to the non-diseased controls. Poor dietary antioxidant intake may lead to excessive oxidative damage and has been associated with age-related diseases. Furthermore, the aged lowlanders seem to have an adequate intake of dietary antioxidants compared to the highlanders’ participants.