['The McGill Quality of Life Questionnaire (MQOL) is being developed to correct what we perceive to be a flaw in existing quality of life instruments: neglect of the existential domain.', 'This study reports the first use of MQOL for people with cancer at all phases of the disease, including those with no evidence of disease after therapy.', 'The data suggest that MQOL is comprised of an item measuring physical well-being and four subscales: physical symptoms, psychological symptoms, existential well-being, and support. MQOL is acceptable to oncology outpatients. Correlation of the MQOL total and subscale scores with a single item scale measuring overall quality of life and with the Spitzer Quality of Life Index suggests that MQOL has construct and concurrent validity.'] Is existential well-being an important determinant of quality of life . Evidence from the McGill Quality of Life Questionnaire?