A randomized trial compared balanced crystalloids (lactated Ringer's solution or Plasma-Lyte A) with saline (0.9% sodium chloride) in critically ill adults. The study enrolled 15,802 patients across five intensive care units, with randomization based on the ICU's assignment to use either solution. The primary outcome was a major adverse kidney event within 30 days, defined as death, new renal-replacement therapy, or persistent renal dysfunction. Balanced crystalloids were associated with a lower rate of this composite outcome (14.3% vs. 15.4%) and lower in-hospital mortality (10.3% vs. 11.1%). The incidence of new renal-replacement therapy was similar (2.5% vs. 2.9%), and persistent renal dysfunction was also similar (6.4% vs. 6.6%). These results suggest that balanced crystalloids may reduce the risk of adverse kidney events compared to saline. The study was conducted in a pragmatic, cluster-randomized, multiple-crossover design, with data collected from electronic health records. The trial was overseen by an independent data and safety monitoring board. The results were consistent across multiple sensitivity analyses. The study highlights the potential benefits of using balanced crystalloids over saline in critically ill patients, particularly in those with sepsis or receiving larger volumes of isotonic crystalloid. However, the study also acknowledges limitations, including the single-center setting and potential bias from clinician awareness of the assigned crystalloid. The findings suggest that balanced crystalloids may reduce the risk of death, new renal-replacement therapy, or persistent renal dysfunction in critically ill adults.A randomized trial compared balanced crystalloids (lactated Ringer's solution or Plasma-Lyte A) with saline (0.9% sodium chloride) in critically ill adults. The study enrolled 15,802 patients across five intensive care units, with randomization based on the ICU's assignment to use either solution. The primary outcome was a major adverse kidney event within 30 days, defined as death, new renal-replacement therapy, or persistent renal dysfunction. Balanced crystalloids were associated with a lower rate of this composite outcome (14.3% vs. 15.4%) and lower in-hospital mortality (10.3% vs. 11.1%). The incidence of new renal-replacement therapy was similar (2.5% vs. 2.9%), and persistent renal dysfunction was also similar (6.4% vs. 6.6%). These results suggest that balanced crystalloids may reduce the risk of adverse kidney events compared to saline. The study was conducted in a pragmatic, cluster-randomized, multiple-crossover design, with data collected from electronic health records. The trial was overseen by an independent data and safety monitoring board. The results were consistent across multiple sensitivity analyses. The study highlights the potential benefits of using balanced crystalloids over saline in critically ill patients, particularly in those with sepsis or receiving larger volumes of isotonic crystalloid. However, the study also acknowledges limitations, including the single-center setting and potential bias from clinician awareness of the assigned crystalloid. The findings suggest that balanced crystalloids may reduce the risk of death, new renal-replacement therapy, or persistent renal dysfunction in critically ill adults.