Exposure of CHO-K1 cells to three different inhibitors of glycolysis, prior to treatment with a single dose of ionising radiation, reduced their survival. The effects were concentration-dependent but occurred under all conditions where cells were exposed to the inhibitors prior to irradiation. The results are similar to those obtained by this group when glycolysis was altered using analogues of D-glucose or by blocking the pyruvate----lactate reaction using added lactate or oxamate. They support data from other workers suggesting a role for energy metabolism in the final expression of radiation damage.