Four methods of assessment of the quality of life were compared in 100 patients with advanced cancer. All showed highly significant correlations with each other. In particular, a single-item linear analogue self-assessment (LASA) which indicated the patients' general feeling of well-being showed a highly significant correlation with multiple item measures of the quality of life (interviewer-administered and self-administered versions of a 5-item quality of life index, and a 21-item LASA). The LASA indicating well-being was compared in a further 30 patients with a similar single-item LASA in which the term 'quality of life' was used. This comparison again showed a highly significant correlation. It is concluded that a single-item LASA asking the direct question "How would you rate your quality of life today?" is a valid and reliable indicator of the quality of life of patients with cancer.