The experiment was carried out on 4 pregnant goats at age 23 years. Changes in basic indices of renal function were analysed in the scope of hydroelectrolyte management in the consecutive five months of gestation. Blood and urea samples were collected fortnightly during the first three months of gestation, and weekly during the remaining two months. The analyses included urea volume and glomerular filtration rate, as well as blood plasma concentration, clearance, tubular reabsorption and excretion of sodium, potassium, chlorides and total osmotically active substances.