The authors evaluated in 82 patients 228 findings of renal functions. Twenty-nine patients with a total number of 113 findings died. In those who died frequently the values of renal functional parameters were beyond the reference limits, indicating various failures (high serum creatinine, high serum urea, elevated fractional osmolal and water excretion, reduced creatinine clearance). In those who died tubular osmotic diuresis was more frequent, while overflow osmotic diuresis was found mostly in the surviving patients. By means of linear discrimination analysis vectors of parameters were assessed suitable for evaluation of the relationship of renal functions and the prognosis and functional shapes of so-called renal prognostic indicators. In the calculation of renal prognostic parameters the following ones prove useful: serum creatinine (SKrea), creatinine clearance (CKrea), serum osmolality (SOsm), osmolality of urine (UOsm), sodium cation in serum (SNa), fractional excretion of water (FeH2o), of potassium (FeK), osmolal (FeOsm), urinary excretion per 24 hours of creatinine (DuKrea), sodium (DuNa) and potassium (DuK). The best prognostic effectiveness was obtained from the calculation of the renal prognostic indicator (RPU) according to the following equation: RPU = SOsm.0.0178--CKrea.0.944 + FeK.0.854 + + DuKrea.0.0665--DuNa.0.0022 + DuK.0.0047--4.931. The RPU value rises with the deteriorating prognosis of the patients; in those who died it reaches more frequently positive values, in surviving patients the values are negative. By reclassification, using this prognostic index, 82% of the patients with a favourable prognosis and 68% with a poor prognosis (those who died) were correctly classified, i. e. a total of 74% patients.