<b>Background:</b> Obstructive sleep apnea (OSA) has been linked to attention deficit hyperactivity disorder (ADHD), with few studies at high altitude. <b>Objective:</b> To describe clinical and Polysomnographic (PSG) characteristics in children with symptoms of OSA who were evaluated for ADHD at high altitude. <b>Methods:</b> 70 children aged 4-9 years living at 2,560 m underwent PSG were included. Electronic medical record and PSG parameters and demographic data were analyzed. Qualitative variables are presented in absolute and relative percentage frequencies, quantitative variables presented in averages, standard deviations, and ranges. Statistical analysis was performed using chi square and Kruskal-Wallis test <b>Results:</b> The distribution of the sample was: 75.7% boys, mean age 8.2 years, 25.7% had OSA and 51.4% had ADHD. There were not statistically significant differences between ADHD and non-ADHD. Sleep architecture was abnormal in 44.3% of patients mostly due to low sleep REM in children with mild OSA (<0.001) and of these 44.4% had ADHD. The average SaO2 was normal in most children (mean SaO2 93.1%) and 89.1% in OSA children and no statistically significant differences were found between ADHD and non-ADHD patients. ADHD children require more frequent use of antihistamines, inhaled steroids, and montelukast. <b>Conclusions:</b> ADHD is frequent in children with OSA at high altitude. Larger multicentric studies are needed to search associations between these conditions in children living in high altitude.