The question addressed by the studyChronic exposure to hypoxia increases pulmonary artery pressure (PAP) in highlanders, but the criteria for diagnosis of high-altitude pulmonary hypertension (HAPH) are debated. We assessed cardiac function and PAP in highlanders at 3250 m and explored HAPH prevalence using different definitions.Patients and methodsCentral Asian highlanders free of overt cardiorespiratory disease, permanently living at 2500–3500 m compared to age-matched lowlanders living <800 m. Participants underwent echocardiography close to their altitude of residence (at 3250 mversus760 m).Results173 participants (97 highlanders, 76 lowlanders), mean±sdage 49±9 years (49% females) completed the study. Results in lowlandersversushighlanders were systolic PAP (23±5versus30±10 mmHg), right ventricular fractional area change (42±6%versus39±8%), tricuspid annular plane systolic excursion (2.1±0.3versus2.0±0.3 cm), right atrial volume index (20±6versus23±8 mL·m⁻²), left ventricular ejection fraction (62±4%versus57±5%) and stroke volume (64±10versus57±11 mL); all between-group comparisons p<0.05. Depending on criteria, HAPH prevalence varied between 6% and 35%.The answer to the questionChronic exposure to hypoxia in highlanders is associated with higher PAP and slight alterations in right and left heart function compared to lowlanders. The prevalence of HAPH in this large highlander cohort varies between 6% according to expert consensus definition of chronic high-altitude disease to 35% according to the most recent definition of pulmonary hypertension proposed for lowlanders.