A 6-year retrospective cohort study was conducted among Thai hematologic malignancy (HM) patientsreceiving intensive chemotherapy. Of the 145 eligible patients receiving 893 chemotherapy sessions, 46.9%were female, median age was 52 years, and the most common HM diagnosis was diffuse large B-cell lymphoma(46.2%). Febrile neutropenia (FN) occurred in 14.9% of chemotherapy sessions with an incidence of 24.8 per 1,000chemotherapy cycles per year. Independent factors associated with FN were receiving the first chemotherapy cycle[adjusted hazard ratio (aHR) 4.1], having hemoglobin ≤100 g/L (aHR 3.7) and platelet ≤140,000/μL (aHR 2.7) onchemotherapy day and receiving acute myeloid leukemia regimens (aHR 20.8). Granulocyte colony stimulatingfactor was significantly associated with reduced rate of FN when given in those receiving CHOP regimen. Withthe median follow-up time of 16 months, the overall survival time was significantly longer in patients withoutFN than those with FN (61.7 vs. 20.8 months; p<0.001).