The suggested gas chromatographic vapor phase analysis of the blood for the direct determination of the blood acetate concentration is performed with Soviet equipment and is based on expulsion of acetic acid from its salts and other derivatives after addition of potassium bisulfate and heating of the blood sample at +105 degrees C for an hour in a hermetically sealed flask. To directly measure acetate, a certain vapor phase volume is let into the gas chromatographic evaporator after equal distribution of acetate in the gas and liquid phases is achieved. This method was used to measure the blood acetate levels in the patients with renal insufficiency treated by hemodialysis. The total content of the blood acetate in health is 1.6 +/- 0.3 mmol/l; this value essentially grows in acetate hemodialysis. In some patients acetate levels persist increased between the dialysis courses. The suggested method may be useful for monitoring the blood acetate levels in the patients treated with hemodialysis and for the detection of subjects with acetate intolerance.