Objectives: To (1) compare baseline clinical and demographic characteristics of postacute stroke inpatients who were diagnosed with first-time urinary tract infection (UTI) versus inpatients who were not; (2) compare rehabilitation outcomes between both groups; and (3) examine associations between time to UTI event and risk factors. Design: Retrospective observational cohort study. Setting: Institution for inpatient neurologic rehabilitation. Participants: Inpatients (n=1683) admitted within 3 months poststroke to a rehabilitation facility between 2005 and 2023. Interventions: Not applicable. Main Outcome Measures: Functional independence measure (FIM), functional ambulation categories (FACs) at admission. Cox proportional hazard models analyzed the association between UTI event timing and risk factors. Results: Of the (n=1683) included patients, 196 (11.6%) experienced a UTI. In 32.1% of cases, the UTI occurred during the first week after admission to rehabilitation and 47.9% of UTIs occurred during the first 2 weeks. The median (interquartile range) time to UTI was 16 (5-37) days since admission. Most common germs were Escherichia coli (40.5%), Klebsiella pneumoniae (23.7%), and Pseudomonas aeruginosa (6.4%). Patients who acquired a UTI had older age, higher stroke severity, higher proportion of dysphagia, hypertension, neglect, bilateral affectation, atrial fibrillation, hemiplegia, lower levels of functional independence, and lower FAC. We identified no differences in gender, type of stroke (ischemic or hemorrhagic), time to admission, aphasia, diabetes, dyslipidemia, chronic obstructive pulmonary disease, dominant side affected, and educational level between both groups. Patients with UTI presented significantly poorer rehabilitation outcomes including lower discharge FIM and FAC, larger length of stay, lower FIM efficiency, and decreased FIM effectiveness. Multivariable Cox proportional hazards identified hypertension HR=1.60 (1.13-2.27), admission FIM HR=0.98 (0.97-0.99), admission body mass index HR=0.96 (0.93-0.99), and admitted with catheter HR=1.80 (1.22-2.64) as significant predictors of time to first UTI event (Concordance-index=0.754). Conclusions: UTIs identification, characterization, and predictive factors can support postacute stroke mitigation strategies to minimize UTI-related complications and optimize rehabilitation outcomes. Archives of Physical Medicine and Rehabilitation 2025;106:729-37 (c) 2024 by the American Congress of Rehabilitation Medicine.