OBJECTIVE：To investi gate the role of clinical pharmacists in the treatment of delayed excretion of acute renal failure （ARF） with epileptic seizure caused by HD-MTX in a patient ，and to provide reference for rational drug use and pharmaceutical care in such type of patients. METHODS ：A patient with diffuse large B-cell lymphoma was given HD-MTX for chemotherapy，and ARF caused by delayed methotrexate excretion occurred on the second day after methotrexate administration. Clinical physicians adjusted the rescue dose and frequency of calcium folinate but the effect was poor. Clinical pharmacists analyzed the causes of delayed methotrexate excretion by reviewing literature and combining with the patient ’s condition. It was suggested to monitor the blood concentration of methotrexate ，strengthen alkalization and hydration ，increase the volume of intravenous sodium bicarbonate from 125 mL to 250 mL，take Sodium bicarbonate tablets orally ，and monitor the pH value of urine （pH value of urine maintained above 7）. In addition ，the pharmacist told the patient to drink water as much as possible to ensure the daily urine output reached 3 000 to 4 000 mL. The blood concentration of methotrexate was 16.14 μmol/L 44 h after administration ，which proved to be excretion delay. The patient had epileptic seizure on the 13th day after methotrexate medication. The physician gave sodium valproate 0.8 g intravenously to control epilepsy. The clinical pharmacist conducted pharmaceutical care for the patient ，and found that the compliance of the patient taking Sodium bicarbonate tablets and Sodium valproate tablets orally was not good ，so medication education and pharmaceutical care were conducted ，then the patient accepted and took the drugs on time. RESULTS ： The physician adopted the suggestions of the pharmacist to monitor the blood concentration of methotrexate and performed symptomatic treatment. The urine volume of the patient increased ，the edema was reduced ，serum creatinine gradually returned to normal，and renal function recovered gradually ；the symptoms of epilepsy was controlled. CONCLUSIONS ：In the treatment process of ARF complicated with epileptic seizure caused by excretion delay of HD-MTX ，the clinical pharmacist assisted physician to improve the treatment plan and conducted pharmaceutical care and medication education for the patient ，therefore ensure the safe and rational use of drugs .