A trial included 200 women: 50 control women with healthy pregnancy, 150 women with pre-eclampsia (PE). Daily salt and potassium intake was estimated based on calculation of 24-hour urinary sodium U[Na+] and potassium U[K+] excretion. At the end of the measurements, the pregnant women with PE were divided into tertiles according to U[Na+]/[K+]: low Na/K group (n=50, mean U[Na+]/[K+]: 1,04±0,32), medium Na/K group (n=50, mean U[Na+]/[K+]: 2,49± 0,54), high Na/K group (n=50, mean U[Na+]/[K+]: 6,62±3,41). The mean systolic and diastolic blood pressure levels were significantly lower in low Na/K group compared with medium or high Na/K groups (p=0.024, p=0.0002; respectively). Serum creatinine was significantly lower in low Na/K group than high Na/K group (p=0.025). Frequency of severe pre-eclampsia is lower in low Na/K group than medium or high Na/K groups (p=0.002, p=0.0001; respectively). Birth weight and gestational age at birth were higher in low Na/K group compared with high Na/K group (p=0.045, p=0.0002; respectively). After adjusting for covariates, blood pressure and creatinine levels were independently associated with 24 hours urinary [Na+]/[K+].