Earle's Strain L cells were cultured in quantity, so that respiration and glycolysis could be adequately determined. Oxygen uptake was highest the day following renewal of culture medium. Little respiration occurred in the absence of glucose, respiration was moderate (Qo2 = 9.4). respiratory quotient was unity (R.Q. = 1.0). anaerobic glycolysis was low (QLAN2 = 3.5), aerobic glycolysis was low (QLAO2 +CO2 = 1.5) and respiration was stimulated 251% when p-phenylenediamine was added. The metabolism of Strain L cells is like that of most normal tissue.