OBJECTIVE： To reduce ADEs due to potential drug interaction （short for drug interaction） by improving medical staffs’ recognition， and to provide reference for making clinical guidelines for chronic disease. METHODS：  According to the Survey Reprots on Chinese Resident’s Nutrition and Chronic Disease and related literatures， nine common chronic diseases （hypertension， type 2 diabetes mellitus， dyslipidemia， depression， primary lung cancer， rheumatoid arthritis， ischemic stroke， chronic heart failure and chronic obstructive pulmonary disease） and latest corresponding clinical guidelines， developed by the Chinese Medical Association or National Health and Family Planning Commission were selected to evaluate the improvement of drug interaction in the guidelines. Retrieving Micromedex， Stockley’s Drug Interactions， Medscape， Adverse drug interactions： A Handbook for prescribers and drug instructions， centered on the clinical guidelines for hypertension， type 2 diabetes and dyslipidemia， which were most likely to coexist with other chronic diseases and had the highest incidence， the number of drug interactions （mild/medium and severe drug interaction） of drugs recommended by 3 chronic disease guidelines and 8 other guidelines were counted， and drugs with a large number of severe drug interactions were also counted. RESULTS： There was no guideline to discussing the interaction between recommended drugs for comorbidity. The number of mild/mediuem drug reactions recommended by clinical guidelines for hypertension， type 2 diabetes， dyslipidemia and other 8 disease were 759， 681 and 68， respectively； those of severe drug interaction were 262， 17 and 37， respectively. The drugs with a high number of severe drug interactions were digoxin （24）， aspirin （22）， diuretics （12 kinds of drugs， 14-17）. CONCLUSIONS： When patients suffer from multiple chronic diseases， clinical pharmacists should pay attention to drug interactions. Selected clinical guidelines for chronic diseases still need to be completed the content of drug interactions.