On a farm where the ration of cows contained 88.0 g of butyric acid, an experimental group of cows (n = 8), producing milk containing 7.9 mg or more acetone per litre, was studied for 14 days for the effect of a 250 g supplement of sodium acetate to the ration (combined with single i.m. administration of vitamins A, D2 and E) on selected metabolism parameters and on milk production. As distinct from the control group of cows (n = 8) from the same farm which produced milk containing 3.9 mg or less acetone per litre and which were fed without sodium acetone supplements, a tendency of increased alkaemia of the organism was suggested in the experimental cows. This tendency manifested itself during the trial in increased pH values, increased base excess (BE) and standard bicarbonate (SB) in the blood, and in an increase in the pH value and net acido basic secretion in urine. A decrease was recorded in the concentration of the acetone + acetacetic acid sum, the same as beta-hydroxybutyric acid in blood and the sum of acetone and acetacetic acid in milk (P less than 0.01). An insignificant increase of the activity of gammaglutamyl transpeptidase (GMT) was recorded in the blood serum of the experimental cows and a significant increase occurred in the content of potassium (up to P less than 0.01) and urea (up to P less than 0.01) in urine. The supplement of sodium acetate to the feed ration did not influence the degree of ketonuria and the finding of urobilinogen in urine.(ABSTRACT TRUNCATED AT 250 WORDS)