The behavior of electron swarms in gases in time‐varying ramp electric fields is investigated using a Monte Carlo simulation. In particular, we consider the case of swarms in chlorine gas. Swarm parameters as a function of instantaneousE/N(Eis the electric field andNis the gas number density) for differentdE/dtare determined. At higherdE/dt, all the parameters as a function ofE/Nare shifted to largerE/Nwhen compared to the steady‐state case. The drift velocity curve develops a peak which shifts to higherE/Nand increases in magnitude asdE/dtis increased. Next, we pay attention to the definition of the swarm parameters, where the parameters derived from kinetic theory and by analogy to experiment are compared. For the highdE/dtcases, differences in the swarm parameters at the sameE/Nvalues are caused by the inertia of the electrons and their transient beam‐like high drift velocity, while discrepancies due to the difference between the definitions in the kinetic theory and in the analogy to experiment appear significantly. ©1996 American Institute of Physics.