The culture kinetics of human tumor kidney cells (TCL 598) grown on microcarriers are compared with media initially supplemented with either glucose alone or a mixture of galactose and glucose. Growth rates and maximal cell densities are similar, but cellular death is much slower in galactose than in glucose. Galactose is metabolized at a much slower specific rate than glucose. Cells grown in the galactose medium show a different pattern of lactate and pyruvate metabolism compared to cells grown in the glucose medium. Growth with galactose also favours oxidation of glutamine to alanine.