Aim: To determine role of pharmacists in an antibiotic stewardship program (ASP) for febrile neutropenic patients. Methods: A prospective study in four medical wards at Thammasat University Hospital between August 2019 and April 2020. Two medical wards were designated as the pharmacist-driven ASP group and two other medical wards were designated as a control group. Our primary outcome was to compare appropriate use of target antibiotics between the pharmacist-driven ASP group and control group. Results: The results showed 90 febrile neutropenic events in 66 patients. Choice of an appropriate antibiotic was significantly higher in the pharmacist-driven ASP group than the control group (88.9% versus 51.1%, p<0.001). Furthermore, there was greater appropriateness of the dosage regimen chosen as empirical therapy in the pharmacist-driven ASP group than in the control group (97.8% versus 88.7%, p=0.049) and proper duration of target antibiotics in documentation therapy (91.1% versus 75.6%, p=0.039). Although the pharmacist-driven ASP did not affect 30-day infectious diseases-related mortality and length of stay (p=0.810 and 0.267, respectively), multivariate analysis showed that pharmacist-driven ASP and infectious diseases consultation had favorable impact on 30-day infectious diseases-related mortality in chemotherapy induced febrile neutropenic patients (OR 0.082, 95%CI: 0.009-0.762, P = 0.028). Conclusions: Our study demonstrated that clinical pharmacists could implement an antibiotic stewardship program for febrile neutropenic patients. Pharmacist-driven ASP could be a great opportunity to improve antibiotic appropriateness in febrile neutropenic patients.