Postural orthostatic tachycardia syndrome (POTS) is a chronic, multifactorial syndrome with complex symptoms of orthostatic intolerance. Breathlessness is a prevalent symptom, however little is known about the aetiology. Anecdotal evidence suggests that breathless POTS patients commonly demonstrate dysfunctional breathing/hyperventilation syndrome (DB/HVS). There are, however, no published data regarding DB/HVS in POTS, and whether physiotherapy/breathing retraining may improve patients' breathing pattern and symptoms. The aim of this study was to explore the potential impact of a physiotherapy intervention involving education and breathing control on DB/HVS in POTS. A retrospective observational cohort study of all patients with POTS referred to respiratory physiotherapy for treatment of DB/HVS over a 20-month period was undertaken. 100 patients (99 female, mean (standard deviation) age 31 (12) years) with a clinical diagnosis of DB/HV were referred, of which data was available for 66 patients prepost intervention. Significant improvements in Nijmegen score, respiratory rate and breath hold time (seconds) were observed following treatment. These data provide a testable hypothesis that breathing retraining may provide breathless POTS patients with some symptomatic relief, thus improving their healthrelated quality of life. The intervention can be easily protocolised to ensure treatment fidelity. Our preliminary findings provide a platform for a subsequent randomised controlled trial of breathing retraining in POTS.