||OBJECTIVE: Most individuals experiencing whiplash accidents recover rapidly. A considerable proportion, however, develop chronic symptoms. Psychological factors may slow recovery, possibly by increasing the likelihood of other symptoms being misattributed to, and amplified by the whiplash injury. We aimed to investigate how pre-injury mental and somatic symptoms, self-rated health, use of health-services and medications, health-behavior and socio-demographics predict the development of chronic whiplash. METHODS: Data from two waves of a large, population based study (HUNT2 (baseline) and HUNT3) were used. Individuals reporting no whiplash at baseline were identified in HUNT3. Characteristics reported at baseline were compared between those who had developed chronic whiplash in HUNT3 (n=199) and those who had not (n=20,600), using Pearson's chi-squared tests, independent sample t-tests and logistic regression analyses. RESULTS: Individuals developing chronic whiplash reported worse baseline health than those reporting no chronic whiplash. Poor self-rated health was a strong risk factor for subsequent chronic whiplash (OR=2.26, 95%CI: 1.68-3.04). Musculoskeletal pain also increased the risk (OR=1.21, 95%CI: 1.15-1.26), as did diffuse somatic symptoms (OR=2.09, 95%CI: 1.47-2.96), use of different health services (OR=1.31, 95%CI: 1.19-1.45), high use of medications (OR=1.28, 95%CI: 1.14-1.43) and symptoms of anxiety (OR=1.93, 95%CI: 1.39-2.68). Physical activity was protective (OR=0.67, 95%CI: 0.49-0.91). Most socio-demographic variables were not significantly associated with chronic whiplash. CONCLUSION: Poor somatic and mental pre-injury health increased the risk of subsequent chronic whiplash. This suggests that chronic whiplash is not merely an organic disorder, and highlights the importance of individual expectations, symptom reattribution and amplification in development of chronic whiplash.