It is hypothesized that excess weight is a risk factor for delayed recovery from neck pain, such as from whiplash injuries. However, the association between obesity and recovery from whiplash injury has not been studied. The authors examined the association between body mass index and time to recovery from whiplash injuries in a population-based cohort study of traffic injuries in Saskatchewan, Canada. The cohort included 4,395 individuals who made an insurance claim to Saskatchewan Government Insurance and were treated for whiplash injury between July 1, 1994, and December 31,1995. Of those, 87.7% had recovered by November 1, 1997. No association was found between baseline body mass index and time to recovery. Compared with individuals with normal weight, those who were underweight (hazard rate ratio = 0.88, 95% confidence interval: 0.73, 1.06), overweight (hazard rate ratio = 1.01, 95% confidence interval: 0.94, 1.09), and obese (hazard rate ratio = 0.99, 95% confidence interval: 0.90, 1.08) had similar rates of recovery, even after adjustment for other factors. The results do not support the hypothesis that individuals who are overweight or obese have a worse prognosis for whiplash.