PURPOSE: We used technetium-99m dimercaptosuccinic acid (DMSA) scintigraphy to identify factors predictive of renal cortical defects in infants <3 months of age with urinary tract infections (UTIs). METHODS: We retrospectively reviewed data on infants <3 months of age with culture-proven UTIs treated at a single center from March 2010 to February 2016. Blood samples were obtained for laboratory evaluation prior to commencement of antibiotic therapy. The therapeutic delay time (TDT) and therapeutic response time (TRT) were recorded. All patients were divided into two groups depending on features of their DMSA scans. We compared the demographic, clinical, and laboratory characteristics of the two groups. RESULTS: A total of 119 infants (94 males and 25 females; mean age, 56.9±21.3 days) were included. Cortical defects were evident in the DMSA scans of 47 cases (39.5%). In infants with such defects, the peak temperatures (38.9±0.57℃ vs. 38.4±0.81℃, P=0.001), the absolute neutrophil counts (8,920±4,460/mm vs. 7,290±4,090/mm, P=0.043), and the C-reactive protein (CRP) levels (6.49±4.33 mg/dL vs. 3.21±2.81 mg/dL, P=0.001) were significantly higher than those in infants without cortical defects. The TDT was also longer in those with cortical defects (P=0.037). CONCLUSION: We found that a TDT ≥8.5 hr (odds ratio [OR] 5.81), a peak temperature ≥38.3℃ (OR 6.19), and a CRP level ≥4.96 mg/dL (OR 7.26) predicted abnormal DMSA scan results in infants <3 months of age with UTIs.