To analyze whether urinary catheterization in a hospital emergency department (ED) affects short-term prognosis in patients with acute heart failure (AHF). We prospectively recorded baseline and other clinical data in a consecutive cohort of ED patients treated for AHF. Crude and adjusted associations were calculated between catheterization and a primary composite outcome (30-day readmission for AHF and/or death) and secondary outcomes (in-hospital mortality, urinary tract infection UTI, and duration of hospital stay.). Nine hundred ninety-one patients were admitted for AHF. The mean (SD) age was 66 (10.5) years; 71% were women. Catheterization was required for 29.2% in the ED. The primary composite outcome was observed in 7.7% of the patients who were not catheterized and 12.8% of the catheterized patients (P = .02). In-hospital mortality occurred in 5.9% and 9.7% of non-catheterized and catheterized patients, respectively (P = .04), and UTIs occurred in 19.1% and 26.6% (P = .01). Twelve of the non-catheterized patients (1.7%) were readmitted for AHF (vs 11 (3.8%) of the catheterized patients (P = .06), and there were no differences between the groups in hospital stay (11 vs 10.9 days, P = .78). In the adjusted analysis of associations between catheterization and the primary outcome the odds and hazard ratios (OR and HR, respectively) were OR, 1.7 (95% CI, 1.1-2.7) (P = .02) and HR, 1.6 (95% CI, 1.1-2.5) (P = .03). For secondary outcomes, significant associations emerged between catheterization and UTIs (OR, 1.8 95% CI, 1.1-2.2; P = .008) and readmission for AHF (OR, 2.9 95% CI, 1.2-7.3; P = .02). Routine insertion of a urinary catheter in patients with AHF in the ED is associated with worse 30-day clinical outcomes.