In this study, pervaporation separation of MeOH/MTBE was investigated by using natural polymer, agarose, as a membrane material. The membranes from agarose permeated MeOH from MeOH/MTBE mixtures by pervaporation. Permselectivity toward MeOH reached over 9x10(5). From pervaporation and sorption data, the permselectivity is due to both solubility selectivity and diffusivity selectivity.