['Although the precipitating events of hepatorenal syndrome (HRS) development have been well characterized, the actual baseline risk of these events resulting in HRS is much less studied.', 'To assess the predictive value of hyponatremia in the development of HRS.', 'We performed a retrospective observational cohort study including consecutive patients with decompensated liver cirrhosis and normal creatininemia admitted to tertiary center in Slovakia. Patients were censored at two months, development of renal failure, classified either as HRS or renal failure not fulfilling criteria of HRS, was the main outcome.', 'Out of 202 patients 18 developed HRS and 14 renal failure not fulfilling the HRS criteria. A significant difference was found between patients with and without HRS in serum sodium (135.76 ± 5.01 vs. 130.78 ± 3.574 mmol/l; p < 0.0001), creatinine, (81 ± 20.11 vs. 98.18 ± 25.032 µmol/l; p = 0.006), bilirubin (90.4 ± 104.82 vs.175.42 ± 174.12 µmol/l; p < 0.0001), MELD (15.17 ± 5.52 vs. 21.61 ± 6.0; p < 0.0001) and MELD-Na score (19.96 ± 6.0 vs. 25.89 ± 4.96; p < 0.0001). Sodium, creatinine, bilirubin, MELD, MELD-Na score were found to be significant predictors of HRS in univariate analysis. Multivariate analysis two prediction models (Model 1: Bilirubin, creatinin, sodium and Model 2: Sodium, MELD) showed that sodium together with creatinine are the strongest HRS predictors, followed by bilirubin or MELD score.'] Does serum sodium identify patients with cirrhosis at high risk of hepatorenal syndrome?