Quantitative biochemical studies were undertaken in order to examine the influence of the accumulation of lipofuscin in secondary lysosomes on cell metabolic activities of normal diploid human glia cells in a stationary cell culture system. Glia cells accumulate lipofuscin as a function of the duration of the stationary cultivation in vitro. The accumulation of lipofuscin can be decreased by the long-term treatment with the pharmacon meclofenoxate (centrophenoxine, Helfergin). Concomitant with the reduction of the accumulated lipofuscin, meclofenoxate-treated glia cells show enhanced rates of RNA synthesis, protein synthesis and glucose uptake. Most likely, in meclofenoxate-treated normal diploid human glia cells in vitro, the utilisation of glucose is shifted from glycolysis to the pentose phosphate pathway. The data suggest that the meclofenoxate-induced reduction of lipofuscin accumulation has a positive effect on cell metabolic functions and causes a delay of the cellular aging of the human glia cells in vitro.