OBJECTIVE：To investigate the role of clinical pharmacists in the therapy of gefitinib-caused liver injury complicated with cholecystitis in a patient with lung adenocarcinoma ，and to provide reference for the therapy of similar type of patients. METHODS ： Clinical pharmacists participated in the treatment for gefitinib-caused liver injury complicated with cholecystitis in a patient with lung adenocarcinoma. The patient took Gefitinib tablets orally for a long time for anti-tumor treatment，and was hospitalized due to abnormal increase of transaminase. The doctors gave intravenous infusion of tiopronin sodium+ acetylcysteine+reduced glutathione+citicoline to protect liver ，but the effect was not good. After consulting the literature and analyzing the patient ’s condition ， clinical pharmacists suggested that gefitinib should be stopped ， and Magnesium isoglycyrrhizinate injection 0.2 g+5％ Glucose injection 250 mL，ivgtt，qd for liver protection treatment. After discharge ，the patient took Gefitinib tablets orally and was admitted to hospital again due to abnormal increase of transaminase ，and suffered from non-infectious and non-calculous cholecystitis. Clinical pharmacists suggested continuing intravenous drip of Magnesium isoglycyrrhizinate injection 0.2 g+5％ Glucose injection 250 mL，qd for liver protection treatment ，oral administration of Danshu capsules 0.9 g，tid for conservative treatment ；at the same time ，closely monitoring the changes of related indicators. After discharge，clinical pharmacists instructed patients to stop gefitinib ，and take Icotinib hydrochloride tablets 0.125 g，tid+Compound Taxus capsules 0.6 g，tid for anti-tumor treatment. RESULTS ：The doctors adopted the opinions of clinical pharmacists ，and the transaminase levels returned to normal ，and the symptoms of cholecystitis basically subsided. CON CLUSIONS：In the treatment of gefitinib-caused liver injury complicated with cholecystitis in patients with lung adenocarcinoma ， clinical pharmacists 135） assisted doctors to improve the treatment plan and ensure the effectiveness of drug use.