This Letter discusses the use of molecular dynamics simulations to interpret molecular beam deflection experiments. The method consists in calculating the rotational motion of the molecule as it enters the electric field and proceeds within the field, by numerically solving the equations of motion. This approach is suited to polar molecules of any size, any symmetry and at any temperature. It provides a very general framework for simulating the manipulation of rigid and neutral gas phase molecules with external fields. (c) 2006 Elsevier B.V. All rights reserved.