Uptake kinetics and contents of GABA in cultured, normal (i.e. nontransformed) glia cells obtained from the brain hemispheres of newborn mice were measured together with the activity of the GABA transaminase. During three weeks of culturing the activity of the transaminase rose from a low neonatal value toward the level in the adult brain. The uptake kinetics indicated an unsaturable component together with an uptake following Michaelis-Menten kinetics. Both theK m (40 μM) and theV max (0.350 nmol×min(-1)×mg(-1) cell protein) were reasonably comparable to the corresponding values in brain slices, and theV max was much higher than that reported for other glial preparations. The GABA content was low (<5 nmol/mg cell protein), which is in agreement with the high activity of the GABA transaminase.