This observational study aimed to investigate the relationship between regional cerebral oxygen saturation (rSO(2)) during the 6-minute walk test (6-MWT) and the demographic/clinical features of patients with pulmonary arterial hypertension (PAH). Cerebral oxygenation was evaluated during the 6-MWT in 20 pediatric patients with PAH aged >= 7 years [13 male, 7 female; median age 12.25 (range 7-18) years]. In all patients, regional cerebral oxygen saturation (rSO(2)), arterial oxygen saturation (SpO(2)), and heart rate (HR) were measured using near-infrared spectroscopy (NIRS) for 2 min before the test, during the 6-MWT test, and 2 min after the test. The relationship between the changes in rSO(2), heart rate, and SpO(2) values and clinical and laboratory features was compared statistically. The mean pulmonary arterial pressure (mPAP) was 77 (range 25-126) mmHg, and the median 6-minute walk distance ( 6-MWD) was 427.5 (300-570) m. The changes in rSO(2) measurements ranged between 3.41 and 21.8%, and 70% of the patients had a greater than 10% decrease in rSO(2) during the test compared with baseline. Eight patients showed a decrease in rSO(2) without SpO(2) changes. The present study demonstrated a significant decrease in cerebral oxygenation in pediatric patients with PAH during the 6-MWT. We hypothesized that using a combination of the 6-MWT and regional cerebral oxygenation monitoring in pediatric patients with PAH in order to evaluate exercise capacity, as a reflection of reduced daily activities, would provide more precise predictive values than the 6-MWT alone.