Breathlessness is common in advanced disease and can have a devastating impact on patients and carers. Research on the management of breathlessness is challenging. There are relatively few studies, and many studies are limited by inadequate power or design. This paper represents a consensus statement of the National Cancer Research Institute Palliative Care Breathlessness Subgroup. The aims of this paper are to facilitate the design of adequately powered multi-centre interventional studies in breathlessness, to suggest a standardised, rational approach to breathlessness research and to aid future 'between study' comparisons. Discussion of the physiology of breathlessness is included.