The effects of glucose and L-glutamine on the growth and maintenance of recombinant Chinese hamster ovary (CHO) cells were investigated in batch cultures. Glutamine was significant for cell growth although glutamine limitation was not observed above 0.26 mmol l(-1). Glutamine was not critical to cell maintenance since cells grew a little and cell viability was as high as 90% for 40 h after the depletion of glutamine provided glucose was available. Cell growth was glucose concentration-independent at concentrations above 6 mmol l(-1) and cell viability rapidly declined on the depletion of glucose even though glutamine was available. In conclusion, glutamine cannot support recombinant CHO cell growth and maintenance as the sole energy/carbon source substrate. (C) 2003 Elsevier Ltd. All rights reserved.