There is growing evidence for the idea that in back pain patients, pain-related fear (fear of pain/physical activity/(re)injury) may be more disabling than pain itself. A number of questionnaires have been developed to quantify pain-related fears, including the Fear-Avoidance Beliefs Questionnaire (FABQ), the Tampa Scale for Kinesiophobia (TSK), and the Pain Anxiety Symptoms Scale (PASS). A total of 104 patients, presenting to a rehabilitation center or a comprehensive pain clinic with chronic low back pain were studied in three independent studies aimed at (1) replicating that pain-related fear is more disabling than pain itself (2) investigating the association between pain-related fear and poor behavioral performance and (3) investigating whether pain-related fear measures are better predictors of disability and behavioral performance than measures of general negative affect or general negative pain beliefs (e.g. pain catastrophizing). All three studies showed similar results. Highest correlations were found among the pain-related fear measures and measures of self-reported disability and behavioral performance. Even when controlling for sociodemographics, multiple regression analyses revealed that the subscales of the FABQ and the TSK were superior in predicting self-reported disability and poor behavioral performance. The PASS appeared more strongly associated with pain catastrophizing and negative affect, and was less predictive of pain disability and behavioral performance. Implications for chronic back pain assessment, prevention and treatment are discussed.