This study evaluated the effects of an essential oil mouthwash on radiation induced mucositis of the oropharyngeal area during treatment for head and neck cancers. Nineteen adult patients completed the randomized placebo controlled trial which involved the use of a gargle containing 2 drops of a 1:1 mix of the essential oils of manuka (Leptospermum scoparium) and kanuka (Kunzea ericoides) in water. Those in the essential oil gargle group were observed to have a delayed onset of mucositis and reduced pain and oral symptoms relative to placebo (gargling with water) and the control ('usual care') groups. In addition those in the essential oil group were seen to have less weight loss (1% loss) than the other two groups (control 2.5%, placebo 4.5%). However a significant limitation in this study was the small sample size. Although the results from this feasibility study support the hypothesis that very small volumes of manuka and kanuka used in a gargle can provide a positive effect on the development of radiation induced mucositis, further research is required to confirm this finding. Randomization was applied according to the timing of the patient's entering the trial as well as their physical ability to gargle. Confirmation of these findings would pave the way for introduction of a simple, yet effective treatment for a condition which causes considerable discomfort and for which there is currently no definitive treatment.