High sodium diets have been shown to enhance water intake and urine output, a potential benefit in the management of lower urinary tract diseases. However, one study suggested that high salt (sodium chloride) diets might have adverse effects on the kidneys [Kirk CA, Jewell DE, Lowry SR. Effects of sodium chloride on selected parameters in cats. Vet Ther 2006; 7: 333–46]. Therefore, the objective of this controlled, prospective study was to evaluate the effects of diets with different salt content (1.11% sodium and 1.78% chloride versus 0.55% sodium and 1.02% chloride, dry matter (dm)) when fed to mature cats (mean age 7.0 years; 12 cats per group) over a 6-month period. Food intake, body weight, bone mineral content, total body hydration status, blood pressure, and markers of renal function were unaffected by salt intake, and no adverse effects were observed. When a subset of cats ( n=9) with an initial serum creatinine ≥1.6 mg/dl was evaluated separately, there remained no evidence of adverse effects associated with increased salt intake. These results are consistent with the majority of other studies evaluating sodium intake in cats, as well as with the National Research Council's assessment, all of which indicate that sodium at 1.5% of the diet dm is not harmful to healthy cats.