Abstract: Pure crystalline anthaquinone derivatives have been isolated from Chinese rhubarb, and their effects on the respiration and glycolysis of Ehrlich ascites carcinoma cells are investigated. Preliminary results showed that the respiration of Ehrlich ascites carcinoma cells was strongly inhibited by emodin. The concentration of 50% inhibition, was 20μg/ml. Rhein showed moderate inhibition, aloe-emodin and chrysophanoi showed only weak inhibition:Emodin was also shown to inhibit the oxidation and dehydrogenation of some amino acids and intermediate products of carbohydrates metabolism in Ehrlich ascites carcinoma cells. In the case of oxidation and dehydrogenation of lactate, the percentages of inhibition were 87% and 91% respectively.Rhein exhibited strong inhibitory effects on the glycolysis of Ehrlich ascites carcinoma ceils. At the concentration of 20 μg/ml, the percentage of inhibition was 60%. Conversely, emodin was found to stimulate glycolysis.The respiration of normal tissues such as kidneys and liver homogenates were almost unaffected by emodin (25 and 50 μg/ml) and rhein (25 μg/ml), but rhein, at the concertration of 50μg/ml showed definite inhibitory effect on brain tissue homogenates.From the present studies, it seems that the antitumor activities of emodin and rhein are probably due to interference with the energy-yielding system.