Purpose: Urinary tract infection (UTI) is one of the major febrile diseases in children. It has been observed that a certain portion of UTI patients develops transient neutropenia during the disease course. This study aimed to determine predictive factors associated with the risk of neutropenia during the course of UTI. Methods: We retrospectively reviewed the records of pediatric (age under 18) patients who were admitted and treated for febrile UTI from September 2015 to July 2017 at our center. Fever was defined as body temperature of 38’C or higher and pyuria as presence of white blood cells (WBC)＞3 per high power field (HPF). Neutropenia was defines as absolute neutrophil count (ANC) of less than 1000/uL with/without leukopenia. During the study period, there were 120 patients with febrile UTI and 22 were excluded for not having checked ANC to finally include 98 eligible patients. We used chi-square, Mann-Whitney U, binary logistic regression and linear regression to identify associated clinical factors for neutropenia. Results: There were 98 patients; 8 neutropenic and 90 not neutropenic. The median age at admission of the 98 patients were 9.0 [1-180] months. ANC at nadir was 632[331-846] for the neutropenic group and 9710 [1075-26769] for the non-neutropenic group. The lymphocytes counts were significantly increased for the neutropenic group (74.9% vs 40.2%, P0.001). Other clinical factors were not significantly different between the two groups. Although we performed binary logistic regression analysis for being neutropenic, no factors had statistical significance (data not shown). We thereby performed linear regression for ANC count itself, in result to show that lower serum levels of C-reactive protein (CRP) ( P 0.001), higher level of sodium( P=0.003), and lower level of cholesterol ( P=0.023) were significantly associated with lower ANC count. Stepwise multivariate analysis revealed that lower CRP and cholesterol remained significant ( P0.001, and 0.009, respectively). Conclusions: In this study, we have analyzed a cohort of pediatric patients with febrile urinary tract infection in an attempt to seek factors affecting transient neutropenia appearing during the disease course. Lower CRP and cholesterol appear to be consistent risk factors for lower ANC. Further studies in a larger scale are warranted to better elucidate and confirm the risks.