AIM: To analyze the Pharmaceutical Care Network Europe (PCNE) classification system used for evaluating the drug related problems (DRPs) of tacrolimus concentration fluctuations in kidney transplant recipients. METHODS: Kidney transplant recipients were selected as the study subjects, who experienced fluctuations in tacrolimus blood concentrations and clinical pharmacist intervention during outpatient follow-up. PCNE (9.0) classification system was used to evaluate the DRPs of tacrolimus. And the DRP problems, causes, intervention plans, acceptance and status were analyzed. RESULTS: A total of 700 kidney transplant recipients were enrolled from July 2019 to December 2021, and 1014 DRPs were found. The problems of DRPs included the occurrence of adverse drug events (P2.1, 60.16%) and poor treatment outcomes (P1.2, 39.84%); The main reasons included dosage selection (C3, 43%), others (C9, 38.4%), and drug selection (C1, 9.41%); Clinical pharmacists actively intervened at the recipient level (I2, 98.92%) and drug level (I3, 1.08%); The acceptance rate of the intervention plan (A1.1+A1.3) reached 98.62%, and the complete implementation rate (A1.1) reached 72.09%; 79.29% of DPRs were fully or partially resolved (O1.1 and O2.1). CONCLUSION: Clinical pharmacists can use PCNE to evaluate tacrolimus therapeutic drug monitoring (TDM) related DRPs, help standardize TDM pharmaceutical service models, standardize TDM abnormal result interpretation and intervention workflows, and promote safe and rational drug utilization.