Background and Purpose: While an association between hyperchloremia and worse outcomes, such as acute kidney injury and increased mortality, has been demonstrated in hemorrhagic stroke, it is unclear whether the same relationship exists after acute ischemic stroke. This study aims to determine the relationship between moderate hyperchloremia (serum chloride ≥115 mmol/L) and acute kidney injury in patients with ischemic stroke. Methods: This is a multicenter, retrospective, propensity-matched cohort study of adults admitted for acute ischemic stroke. The primary objective was to determine the relationship between moderate hyperchloremia and acute kidney injury, as defined by the Acute Kidney Injury Network criteria. Secondary objectives included mortality and hospital length of stay. Results: A total of 407 patients were included in the unmatched cohort (332 nonhyperchloremia and 75 hyperchloremia) and 114 patients (57 in each group) were matched based upon propensity scores. In the matched cohort, hyperchloremia was associated with an increased risk of acute kidney injury (relative risk 1.91 [95% confidence interval 1.01-3.59]) and a longer hospital length of stay (16 vs 12 days; P = .03). Mortality was higher in the hyperchloremia group (19.3% vs 10.5%, P = .19), but this did not reach statistical significance. Conclusions: In this study, hyperchloremia after ischemic stroke was associated with increased rates of acute kidney injury and longer hospital length of stay. Further research is needed to determine which interventions may increase chloride levels in patients with acute ischemic stroke and the association between hyperchloremia and clinical outcomes.