OBJECTIVE: To examine the psychometric properties of the revised Piper Fatigue Scale (PFS) in Dutch cancer patients. STUDY DESIGN AND SETTING: Participants were 64 patients with lung (any stage, nonsurgery) and breast (any stage) cancer, selected for curative high-dose radiotherapy (>/=50 Gy). Prior to radiotherapy, patients completed the revised PFS (translated into Dutch), the Multidimensional Fatigue Inventory (MFI), and the Rotterdam Symptom Checklist (RSCL). Reliability and construct and criterion validity of the PFS were investigated. RESULTS: Overall, the structure of the Dutch revised PFS appeared appropriate, with corrected item-subscale correlations being higher than the correlations of the same item with the three other subscales; furthermore, internal consistency was excellent (Cronbach's alpha >/=0.90). Lung cancer patients were significantly more tired then breast cancer patients, supporting construct validity. Criterion validity was also satisfactory, with highest correlations of PFS total fatigue with the MFI subscale general fatigue (0.84) and RSCL overall quality of life score (0.74). Internal consistency was similar in Dutch and U.S. breast cancer patients; fatigue scores were lower on several PFS subscales in the Dutch study population. CONCLUSION: Psychometric properties of the Dutch version of the revised PFS, as tested in cancer patients prior to radiotherapy, were satisfactory. AD - Department of Epidemiology, NUTRIM, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands.