Background: Nearly all clinical trials investigating patients with pulmonary arterial hypertension (PAH) have used the 6-min walk test (6MWT) to evaluate exercise tolerance. The incremental shuttle walk test (SWT), however, has been proposed as a more valid and reproducible alternative to the 6MWT in the evaluation of exercise tolerance in patients with chronic obstructive pulmonary disease. The efficacy of SWT in clinical practice to evaluate the exercise capacity of patients with PAH was investigated. Methods and Results: The peak oxygen consumption (pVO₂) and oxygen consumption at anaerobic threshold (VO₂ at AT), the gold standard for measurement of exercise tolerance, 6MWT and SWT were measured in 19 clinically stable PAH patients (WHO functional class II–III) and the data compared. There was a higher correlation between SWT walk distance and pVO₂ than between 6MWT walk distance and pVO₂ (r=0.866 and 0.765, respectively; P<0.05), and a higher correlation between SWT walk distance and VO₂ at AT than between 6MWT walk distance and VO₂ at AT (r=0.775 and 0.587, respectively; P<0.05). No adverse events occurred during the exercise tests. Conclusions: SWT is a better reflection than 6MWT of exercise tolerance in PAH patients, and thus is a preferable alternative for assessment of exercise tolerance in PAH patients.  (Circ J 2014; 78: 215–221)