A comprehensive review with 70 refs. (including authors' own works) covering extraction of Zn(II) and Cd(II) ions from aqueous chloride media with tertiary amines and quaternary ammonium salts, separation of the ions in relation to pH of the aqueous phase, use of bulk, supported, emulsion and polymer inclusion membranes (PIM), and selective transport of Zn(II) and Cd(II) ions from aq. chloride source phase through a PIM containing cellulose triacetate (matrix), o-nitrophenyl pentyl ether (plasticizer) and trioctyl amine (ion carrier). A long-duration transport experiment showed the PIM to be quite durable. As the concentration of HCl in the aq. source phase was raised, the transport selectivity of Cd(II)/Zn(II) diminished.