Aims: We sought to examine sex differences in congestion in patients hospitalized for acute heart failure (AHF). Understanding congestive patterns in women and men with AHF may provide insights into sex differences in the presentation and prognosis of AHF patients. Methods and results: In a prospective, two-site study in adults hospitalized for AHF, four-zone lung ultrasound (LUS) was performed at the time of echocardiography at baseline (LUS1) and, in a subset, pre-discharge (LUS2). B-lines on LUS and echocardiographic images were analysed offline, blinded to clinical information and outcomes. Among 349 patients with LUS1 data (median age 74, 59% male, and 87% White), women had higher left ventricular ejection fraction (mean 43% vs. 36%, P < 0.001), higher tricuspid annular plane systolic excursion (mean 17 vs. 15 mm, P = 0.021), and higher measures of filling pressures (median E/e′ 20 vs. 16, P < 0.001). B-line number on LUS1 (median 6 vs. 6, P = 0.69) and admission N-terminal pro-B-type natriuretic peptide levels (median 3932 vs. 3483 pg/mL, P = 0.77) were similar in women and men. In 121 patients with both LUS1 and LUS2 data, there was a similar and significant decrease in B-lines from baseline to discharge in both women and men. The risk of the composite 90 day outcome increased with higher B-line number on four-zone LUS2: unadjusted hazard ratio for each B-line tertile was 1.86 (95% confidence interval 1.08–3.20, P = 0.025) in women and 1.65 (95% confidence interval 1.03–2.64, P = 0.037) in men (interaction P = 0.72). Conclusions: Among patients with AHF, echocardiographic markers differed between women and men at baseline, whereas B-line number on LUS did not. The dynamic changes in B-lines during a hospitalization for AHF were similar in women and men.