Three prototypes of full molecular drag pump (MDP) have been discussed. The pumping speed is nearly equal to and even could be higher than that of a turbomolecular pump (TMP). Performances at higher pressure are much better than that of TMPs. Configurations of these new pumps are simple. A figure of merit G, defined as product of pumping speed and the logarithm of compression ratio, is introduced to compare the performances between the new MDPs and TMPs. It is possible that these new pumps would be developed in the near future to be viable alternatives to the present TMPs, diffusion pumps, and roots pumps.