This invention is related to a use for a deoxynucleoside/nucleoside combination in the preparation of a medicament that fights tumors. Said deoxynucleoside comprises deoxyadenosine, deoxyguanosine, deoxycytidine, and thymidine and said nucleoside comprises adenosine, guanosine, cytidine, uridine, deoxyadenosine, deoxyguanosine, deoxycytidine, and thymidine. The deoxynucleoside/nucleoside combination of the invention is used to prepare a medicament for many types of common malignant tumors, such as gastric cancer, lung cancer, liver cancer, colon cancer, breast cancer, and tumors of the reproductive system.
