Dyspnoea is one of the most frequent and refractory symptoms in cancer patients. Lack of an appropriate assessment tool for dyspnoea seems to disturb establishment of management strategy. The purpose of this study was to develop and validate a brief self-rating scale to assess the multidimensional nature of dyspnoea in cancer patients. We developed a 12-item scale, the Cancer Dyspnoea Scale (CDS), composed of three factors (sense of effort/sense of anxiety/sense of discomfort), by using factor analysis. One hundred and sixty-six patients with advanced or recurrent lung cancer participated in the validation phase. The CDS showed good feasibility (average time required to complete it was 140 s). Construct validity, confirmed by repeating factor analysis, was good. Convergent validity, confirmed by a relation to Visual Analogue Scale of dyspnoea and modified Borg's scale, was also good (average: r= 0.57 and 0.52, respectively, and both P < 0.001). The CDS had good internal consistency (average Cronbach's alpha = 0.86) and stability (average test-retest reliability r = 0.66, P < 0.005). The present study demonstrated that the CDS is a brief, valid and feasible scale for assessing the multidimensional nature of dyspnoea in cancer patients.