Polatuzumab vedotin(Pola)combination therapy is used for diffuse large B-cell lymphoma(DLBCL)treatment. In clinical trials, more than 90% of the patients have received granulocyte-colony stimulating factor(G-CSF)as primary prophylaxis. However, reports investigating the benefit of prophylactic administration are lacking. In this study, we addressed the incidence of febrile neutropenia(FN)with and without primary prophylaxis with G-CSF combined with Pola therapy. We observed that the incidence of FN with Pola-BR therapy was 0% and 9.5% with and without G-CSF, respectively. The incidence of FN with Pola-R-CHP tended to be higher: 0% and 31.2% with and without G-CSF, respectively. The duration of hospitalization significantly decreased in the Pola-BR group with G-CSF(11 days vs. 18 days in the group without G-CSF), suggesting that prophylaxis might contribute to this reduction. Although not statistically significant, prophylactic G-CSF administration tended to reduce the incidence of Grade 3 or higher leukopenia and neutropenia, suggesting that primary prophylactic G-CSF administration in Pola combination therapy could contribute to reduced hematologic toxicity.