Background: Acute-on-chronic liver failure (ACLF) is a syndrome of acute portal hypertension with high shortterm mortality. ACLF patients have low mean arterial pressure (MAP), systemic vascular resistance, and high cardiac output. This, in turn, leads to an increased incidence of ascites, acute kidney injury, and hyponatremia. We evaluated the role of the early addition of midodrine, which has not been analyzed to date. Methods: ACLF patients who were started on midodrine (Gr. A) in addition to standard of care (SOC) for ascites control were included and compared with those who received only SOC (Gr. B). The aim was to assess the hemodynamics, ascites control, diuretic-related complications, and mortality at 1 month. Results: Forty-five ACLF patients (Gr. A-21; Gr. B-24) were included in the pilot study. At inclusion, the baseline characteristics were similar among the groups. The dose of midodrine was 22.5 (7.5-22.5) mg/day for 22.29 ± 8.75 days in Gr. A. Midodrine significantly improved the MAP and urinary sodium excretion. Only 33.34% of patients required paracentesis in Gr. A compared with 62.5% in Gr. B (p = 0.05). Gr. A patients tolerated a higher dose of diuretics than Gr. B. Diuretic-related complications developed in 54.2% of patients in Gr. B compared with only 23.8% in Gr. A (p = 0.03). Fourteen percent in Gr. A developed side effects to midodrine and required dose modification. Mortality at day 30 was similar in both groups. Conclusion: Addition of midodrine improves the hemodynamics, tolerability of diuretics, and ascites control in ACLF patients. ( J CLIN EXP HEPATOL xxxx;xxx:xxx)