Objectives. To determine the normal values of arterial blood gases in clinically healthy adults living at 3,350 meters of altitude. Materials and methods. The study was conducted in the Santiago district of Cusco, Peru at 3,350 meters of altitude with a sample of 118 subjects determined in a previous pilot study and selected by convenience sampling. The sample included individuals between 20-59 years old with no pulmonary, cardiovascular and hematological medical history, who practice sports less than 60 minutes per day, non smoking, have resided at least 5 years prior to the study in Cusco and were characterized through clinical examination by two internists and pulmonologists as “clinically healthy”. The arterial blood gas collection was standardized for statistical analysis measures of central tendency and dispersion. Student’s t-tests and analysis of variance, linear correlation and multiple linear regression were applied. Results. Women comprised 57.6% of the sample. Respiratory rate averaged 16.2 per minute and BMI 24.8. The blood gas results were: pH 7.42 mEq/L; pO261.08 mm Hg; pCO230.62 mm Hg; pAO262.52 mm Hg; SO291.13%; AaDO20.0 mm Hg; Hto 44.22%; Hb 14.74 mg/dL; CaO218.18 vol%; HCO3 19.74 mmol/L; pO2/FiO2290.79 and Anion Gap 20.99. Using linear regression, it was observed that each year from the age of 20, there was a decrease in pO2(0.122 mm Hg), pAO2(0.08 mm Hg), SO2(0.05%), index pO2/FiO2(0.571 mm Hg) and an increase in pCO2(0.056 mm Hg). Conclusions. The results found with respect to blood gases in this population are different from those residing at sea level and can be used to study other populations residing at a similar altitude.