The change of velocity due to the collision of two vehicles is one of the parameters for evaluation of whiplash injury possibility. This article deals with uncertainties concerning whiplash injuries from various points of view. In the first part of the article the review of literature is introduced concerning various theories about whiplash injury biomechanics, relation between crash severity parameters and whiplash injury risk (one of them is !V) and other factors concerning WAD epidemiology. In the second part of the article the calculation of !V using the Monte Carlo method is introduced, whereby the emphasis is put primarily on the degree of calculation confidence. From the results of the article it is obvious that calculation of !V is uncertain, as is the use of this quantity as a single parameter for whiplash injury risk assessment.