Aim: While various hormones and mediators reduce the urinary excretion of Na, other mediators such as nitric oxide (NO) increase Na excretion. Grape seed proanthocyanidin extract (GSPE) is a molecule that has an antioxidant effect by increasing NO levels. Our study was intended to evaluate the effect of GSPE on Na excretion. Material and Method: Fourteen rats were divided into control and GSPE groups. The control group was given 1 cm3 milk by gavage for one week, while the GSPE group was given 100 mg/kg GSPE. Seventh-day urines were collected from rats monitored over 24 h in a metabolic cage. Urinary Na excretion at the end of 24 h was investigated and the experiment concluded. Results: There was no difference between the control and GSPE groups in terms of weight, solid and liquid food intake and urine volumes. 24-hour urinary Na excretion was higher in the GSPE group (1.43±0.30 g/day) compared to the control group (1.37±0.29 g/day), although the difference was not statistically significant. Na excretion was positively correlated with solid food intake (p=0.029, r=0.583) and urine volume (p<0.001, r=0.806). Discussion: Our study shows, for the first time in the literature, that GSPE increases urinary Na excretion in healthy rats, though not to a statistically significant extent, and that solid food intake and urine volume affect Na excretion. We think that it will be useful for the effect of GSPE on urinary Na excretion in hypertensive rats with impaired Na excretion and balance to be evaluated in future studies.