Objectives: Assessing subjective, patient-reported outcomes such as quality of life (QoL) is essential to health care research. This study aimed to assess the properties of a QoL measure relating to pain and discomfort: the WHOQOL-Pain. Method: Chronic low back pain patients (n=133) completed the WHOQOL-Pain, SF-12, and short-form McGill Pain Questionnaire before treatment started and again 2-4 weeks later. Of these, 76 received a lumbar epidural steroid injection, and 57 were waiting to receive treatment. Results: Overall, there was no significant difference in effect of either epidural injections or no treatment on bringing about an improvement to QoL overtime. Moderate effect sizes were found for 5 facets including pain relief and uncertainty. Small effect sizes were found for 7 facets including vulnerability, fear and worry, anger and frustration. Larger effect sizes were found for those reporting the most improvement in pain. The waiting group reported no significant changes to QoL but small changes for uncertainty. Three of the four new facets were sensitive to change and test-retest reliability (stability) was confirmed in three. Discussion: Although this study was not designed to test treatment effectiveness, the WHOQOL-Pain enables patients to report changes to important aspects of QoL during many diverse interventions for relieving pain. © 2010 by Lippincott Williams & Wilkins.