Effect of cycloheximide, ethidium bromide and hydroxytetracycline on incorporation of label from I-14C-acetate into ubiquinone and cholesterol as well as from diffusively labelled 14C-tyrosine into ubiquinone was studied in slices of rat hypertrophic kidney within 2 days after unilateral nephrectomy. Incorporation of these labels into ubiquinone and of 1-14C-acetate into cholesterol was distinctly increased using slices of hypertrophic kidney. Repeated administration of cycloheximide just after the operation and within 24 hrs after it depressed the kidney hypertrophy, inhibited completely the label incorporation into cholesterol and partially - into ubiquinone. This suggests that the rate of enzymes production, responsible for synthesis of these substances, is increased in hypertrophic kidney. Injection of ethidium bromide after the operation inhibited distinctly the label incorporation into ubiquinone and did not effect on incorporation of 1-14C-acetate into cholesterol. Hydroxytetracycline proved to be ineffective in these labels incorporation. Mitochondrial DNA appears to participate in coding of some functionally active proteins responsible for ubiquinone biosynthesis.