BACKGROUND: Sustained and subtle hyperventilation can result in a wide variety of symptoms, leading to a chronic condition that has been termed hyperventilation syndrome (HVS). Treatment options include physiotherapy, in the form of breathing retraining (BR), but additional approaches aim to reduce the anxiety that is recognized as being a frequent component of this condition. OBJECTIVES: The aim of this study was to evaluate whether acupuncture is an appropriate treatment for HVS to reduce anxiety, and whether a crossover trial is an appropriate study design to evaluate acupuncture in this condition. DESIGN: A single-blind crossover trial was carried out comparing the effects of 4 weeks (30 minutes twice weekly) acupuncture and BR on patients with HVS. SUBJECTS: Ten (10) patients diagnosed with HVS were recruited to the trial and randomized into two groups. Both groups received acupuncture and BR with a washout period of 1 week. OUTCOME MEASURES: The primary outcome measure used was the Hospital Anxiety and Depression (HAD) Scale. Other outcome measures used were the Nijmegen questionnaire and Medical Research Council Dyspnea scale. RESULTS: The results showed statistically significant treatment differences between acupuncture and breathing retraining, in favor of acupuncture. Reductions were found in the HAD A (anxiety) (p = 0.02) and Nijmegen (symptoms) (p = 0.03) scores. There was no statistical evidence of any carryover effects. However, when graphically examining individual anxiety scores, in those who received acupuncture first, there was a reduction in anxiety levels which persisted through the washout period, suggesting that there may have been some carryover effect from this treatment. CONCLUSIONS: This study suggests that acupuncture may be beneficial in the management of HVS in terms of reducing anxiety levels and symptom severity. However, there may be some carryover effect, after acupuncture treatment, which went undetected because the small sample size. This preliminary study provides the basis for a larger, sufficiently powered and methodologically sound trial.