OBJECTIVE： To provide reference for rational drug use in the clinic. METHODS： Irrational medication orders evaluated by the Affiliated Cancer Hospital of Zhengzhou University during Oct. 2014 to Sep. 2015 were arrangemented， summarized and analyzed. RESULTS： A total of 515 inpatient medical records were reviewed and analyzed， among which there were 165 unreasonable medical records and 185 irrational medication orders. Irrational medical records of general surgery department were the most （38 items， accounting for 23.03％）. Irrational drug use mainly included irrational usage and dosage （80.00％）， drug use without indications or not suit indications （7.57％）， inappropriate solvent selection （4.86％）. Including 66.22％ of single overdose， 18.92％ of longer medication duration. CONCLUSIONS： There are many irrational medical orders which should be standardized in our hospital， especially overdose and longer medication duration， which increase financial burden of patient. Pharmacists should?strengthen communication with clinicians， and ?hold rational drug use trainings regularly base on the types of the irrationality. These can help to improve rational drug use and guarantee the safety of drug use.