Whiplash-associated disorders (WADs) have become an increasing problem over the years and many authors have addressed the issue. The aim of the present study is to identify predictors for perceived disability and self-registered pain from a functional perspective, as well as to study the temporal evolution of patients' complaints. Eighty-three patients suffering from pain in the neck following acute whiplash injury were included in the study and they were consecutively monitored at three weeks, three months and one year after injury. The results suggest that a linear combination of sex, self-efficacy and WAD grade significantly explains 24% of the variation observed in pain intensity at the one-year follow-up, whereas a linear combination of self-efficacy, sex and age significantly explains 36% of the variation observed in disability at the one-year follow-up. Five per cent of the patients were non-symptomatic at the first monitoring occasion and 16% at the one-year follow-up. It is concluded that WAD patients' self-efficacy at an early stage after whiplash injury significantly predicts the temporal development of pain intensity and disability. It may therefore be suggested that patients' confidence in performing daily activities should be reinforced in order to optimize treatment after whiplash injury.