Potassium transport in dissociated nerve cell cultures has been studied by analysing 86Rb and ' : K uptake. For this purpose cultures prepared from cerebral hemispheres of both 8-and 14-day-old chick embryos were used in short-term experiments. The potassium pool is in the steady-state in all the cultures. The 86Rb is taken up more rapidly that 42K; however the ratio of amounts of 86Rb and 42K incorporated is constant with time and under different conditions. The run of kinetic curves of uptake has been studied by tracer kinetic model analysis. As a result of this analysis a glial-neuronal interrelationship in transport has been suggested. Furthermore, it was shown that not only glial cells but neurons also take up potassium directly from the medium. Comparing the incorporated amounts in different cultures, a decreased uptake can be seen where glial cells prevail. The significance of this fact is discussed.