This study investigated whether or not inhalation aromatherapy during radiotherapy reduces anxiety. Three hundred and thirteen patients undergoing radiotherapy were randomly assigned to receive carrier oil with fractionated oils, carrier oil only or pure essential oils of lavender, bergamot and cedar wood administered by inhalation concurrently with radiation treatment. Patients underwent assessment by the Hospital Anxiety and Depression Scale (HADS) and the Somatic and Psychological Health Report (SPHERE) at baseline and at treatment completion. There were no significant differences in HADS depression or SPHERE scores between the randomly assigned groups. However, HADS anxiety scores were significantly lower at treatment completion in the carrier oil only group compared with either of the fragrant arms (P = 0.04).