Objective: To determine the test-retest repeatability of the Injury Severity Perception (ISP) score in participants with acute whiplash-associated disorders (WADs). Methods: Consecutive patients with WAD, presenting in the acute stage to a primary care center, were asked to complete the ISP score. ISP was measured with a numerical rating scale that ranged from 0 to 10, on which subjects were asked to rate how severe (in terms of damage) they thought their injury was. The anchors were labeled

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... damage" (0) and "severe, and maybe permanent damage" (10). The ISP questionnaire was administered to the participants at the time of recruitment and again 7 days later. Repeatability was evaluated by calculating percentage agreement and Cohen kappa statistic between the two time points of measurement. Results: A total of 94 subjects (34 males, 60 females, mean age 40.6 ± 10.0 years, range 19-60 years) were included. The mean ISP score was 4.9 ± 1.7 (range 2-9 out of 10) at the time of recruitment and 5.1 ± 2.1 (range 2-9 out of 10) 7 days later. The percentage agreement between the two repeat measures of the ISP was 86% and the kappa coefficient was 0.79. Conclusion: This study suggests that the test-retest repeatability for the ISP is high and that it is thus likely to have a low risk of classification bias in prognostic studies. The ISP likely has adequate reliability for use in epidemiological research of WADs.