Objectives. To conduct a drug utilization review (DUR) on the use of granulocyte colony-stimulating factor (G-CSF) and to study the effectiveness of this agent in preventing the incidence of febrile neutropenia (FN). Methods. Outpatients to whom G-CSF was dispensed were identified and their actual medical records were reviewed to verify patients who received G-CSF for primary prophylaxis. Literature was reviewed to determine the expected incidence and risk of FN for chemotherapy regimens used, and the compliance of prescribers with the institutional guidelines was evaluated. After that, the proportion of patients who developed FN was identified and compared to the expected incidence from literature. Data analysis was performed on the outcome of patient-cycle. Results. Of the 99 patient-cycles, 53 (53%) were compliant with guidelines whereas 46 (47%) were not. FN developed in 12 (12.1%, 95% CI = 5.7, 18.5) while the expected average incidence of FN was 32.7%. Eleven (21%, 95% CI = 10.1, 32.2) of the 53 patient-cycles that were compliant with guidelines developed FN, whereas one patient among the non-compliant group developed FN (2%, 95% CI = 0.0, 6.2). The expected incidence of FN was 42.9 and 21.5%, in the compliant group, and noncompliant group, respectively. Based on expected FN rates, the respective reduction in the incidence of FN was 51, and 90%. Conclusions. Lack of adherence to institutional guidelines was noticed in G-CSF prescribing. Reasons behind poor compliance with the guidelines must be verified and resolved. Prophylactic G-CSF is effective in reducing the incidence of FN; however, further research in a larger population is warranted to confirm these findings.