Fear-avoidance beliefs have been identified as an important psychosocial variable in patients with chronic disability doe to low back pain. The importance of fear-avoidance beliefs for individuals with acute low back pain has not been explored. Seventy-eight subjects with work-related low back pain of less than 3 weeks'duration were studied. Measurements of pain intensity, physical impairment, disability, nonorganic signs and symptoms, and depression were taken at the initial evaluation. Fear-avoidance beliefs were measured with the work and physical activity subscales of the Fear-avoidance Beliefs Questionnaire. Disability and work status were re-assessed after 4 weeks of physical therapy. Patterns of correlation between fear-avoidance beliefs and other concurrently-measured variables were similar to those reported in patients with chronic low back pain. Fear-avoidance beliefs did not explain a significant amount of the variability in initial disability levels after controlling for pain intensity and physical impairment. Fear-avoidance beliefs about work were significant predictors of 4-week disability and work status even after controlling for initial levels of pain intensity, physical impairment, and disability, and the type of therapy received. Fear-avoidance beliefs are present in patients with acute low back pain, and may be an important factor in explaining the transition from acute to chronic conditions. Screening for fear-avoidance beliefs may be useful for identifying patients at risk of prolonged disability and work absence.