Among the >140 million dwellers worldwide up to 10% suffer from chronic mountain sickness (CMS). Patients suffering from this debilitating problem often display increased pulmonary artery pressure (PAP) which may contribute to exercise intolerance and right heart failure. However, there is little information on the usual PAP in these patients.We systematically reviewed and meta-analyzed all data published in English or Spanish until June 2018 on echocardiographic estimations of PAP at rest and during mild exercise in CMS patients.Nine studies, comprising 287 participants fulfilled the inclusion criteria. At rest, the point estimate from meta-analysis of the mean systolic PAP was 28.0 mmHg [95% confidence interval (CI) 26.3, 29.6]. These values are 11% (+2.7 mmHg) higher than those recently meta-analysed in apparently healthy high-altitude dwellers (J Appl Physiol 121:1151-9, 2016). During mild exercise (50 W) the difference in mean systolic PAP between patients and high-altitude dwellers was markedly more accentuated (48.3 36.3 mmHg) than at rest.These findings indicate that in patients with CMS PAP is moderately increased at rest, but markedly increased during mild exercise, which will be common with activities of daily living.