Abstract: OBJECTIVE To investigate the role and effectiveness of clinical pharmacist participated in pharmaceutical care in a lung cancer patient when occurred severe and infrequent adverse drug reactions during chemotherapy. METHODS Clinical pharmacist intervention in one case of lung cancer patient with infrequent adverse reactions during chemotherapy, to intervene clinical medication and actualize pharmaceutical care. RESULTS After active, reasonable and effective treatment, the patient was discharged. The patient was followed up, and the adverse reactions were not occurred. CONCLUSION It is of great significance in the pharmacist's participation in pharmaceutical care in providing pharmaceutical services and promoting the safe and reasonable of drug use.