Natural rubber (NR)/Acrylonitrile butadiene rubber (NBR) blend membranes, prepared by using dicumyl peroxide as the crosslinking agent, were tested for their vapor permeation characteristics. The permeation studies were conducted using three chlorinated hydrocarbons, viz. dichloro methane, chloroform, and carbon tetrachloride. The effects of the blend ratio, compatibilizer, penetrant size, and temperature on the vapor permeability of the membranes were investigated. The permeability of the blends was found to decrease with an increase in the NBR content, which has been attributed to the inherent solvent resistant nature of NBR. The permeation behavior of compatibilized blends was compared with those of the uncompatibilized blends. The separation efficiencies of the membranes were also tested using chloroform/acetone mixtures to complement the observations from the vapor permeation experiments.