Validation of the MFI Cancer Nursing™, Vol. 26, No. 2, 2003 ■ 143 Validation Evidence for the French Canadian Adaptation of the Multidimensional Fatigue Inventory as a Measure of Cancer-related Fatigue Cancer-related fatigue is the most reported symptom among patients with cancer. Researchers in the field of psychooncology have encouraged the development of short instruments, which allow for easier completion by clinical populations while still maintaining solid psychometric properties. The current study examined the validity and reliability of the French Canadian adaptation of the Multidimensional Fatigue Inventory (MFI) among women (n = 277) and men (n = 327) undergoing therapy for breast or prostate cancer, respectively. An exploratory factor analysis of the selected 15-item MFI yielded the following four factors: general/physical, mental, reduced motivation, and reduced activity. This was supported by a confirmatory fac- tor analysis. The reliability, as evaluated by test-retest and Cronbach alpha internal consistency reliability coefficients of the French Canadian shortened MFI, was acceptable. In addition, the four factor-based scores correlated in a theoretically meaningful manner with existing measures of mood disturbance (Profile of Mood States and Hospital Anxiety and Depression Scale), cancer-related stressors (Inven- tory of Recent Life Experiences), coping with illness (Coping with Health Injuries and Problems Scale), quality of life (European Organization for Research and Treatment of Cancer Quality of Life Questionnaire), and insomnia (Insomnia Severity Index), suggesting good construct, convergent, and concurrent criterion validity. Although further validation is recommended, the results for the French Canadian MFI in assessing cancer-related fatigue in both women and men undergoing cancer treat- ments showed good psychometric qualities. © 2003 Lippincott Williams & Wilkins, Inc., Philadelphia Lise Fillion, PhD Céline Gélinas, MSc Sébastien Simard, MPs Josée Savard, PhD Pierre Gagnon, MD K E Y W O R D S Cancer Fatigue measurement French MFI Validation From Laval University, Quebec City, Canada. Supported by a York University Faculty of Arts Research Grant and a CRC Research Grant to the first author. Corresponding author: Lise Fillion, PhD, Faculty of Nursing, University Laval, Quebec, Canada, G1K 7P4 (e-mail: lise.fillion@fsi.ulaval.ca). Accepted for publication December 9, 2002.