Transport of beta-alanine has been demonstrated in membrane vesicles isolated from rat brain, using artificially imposed ion gradients as the sole energy source. The uptake of beta-alanine is strictly dependent on the presence of Na+ and Cl- in the medium, and the process can be driven either by an Na+ gradient (out greater than in) or by a Cl- gradient (out greater than in) when the other essential ion is present. The process is stimulated by a membrane potential (negative inside) as demonstrated by the effect of ionophore valinomycin and anions with different permeabilities. beta-Alanine uptake is inhibited by the presence of GABA.