Abstract： Objective To explore the comprehensive pharmaceutical care for a metastatic colorectal cancer(mCRC)patient with third-line therapy,and provide suggestions for pharmaceutical care in third-line therapy of mCRC.Methods Based on a case and relied on the new model of O2O(Online To Offline)pharmaceutical service,comprehensive pharmaceutical care was carried out for the patient.The method of medication therapy management was explored according to the situation of the third-line therapy for mCRC patients.Results The patient completed three courses of treatment successfully and obtained improvement in laboratory indexes with the cooperation of clinicians and clinical pharmacists.Conclusion Clin-ical pharmacists can assist clinicians in diagnosis and treatment,promote the rationalization and individualization of clin-ical medication,and achieve the aim of safe,effective and economical treatment through comprehensive pharmaceutical care.