In this investigation, oral Kanamycin was administered to young male rabbits for 3 days, the control group receiving only water. Partial hepatectomy was then performed in all of them, and mitochondrial activity, energy charge and portal vein ammonia were measured at 12 and 24 h postoperatively. It was found that mitochondria from oral Kanamycin-treated rabbits have higher respiratory control ratios, higher state 3 respiration and higher P/O ratios than the control group, suggesting a further enhancement of phosphorylative activity. Energy charge in the Kanamycin-treated group showed less acute changes suggesting a positive balance in the energy status of those livers. The ammonia level here was much lower than in the control group. These findings suggest that the removal or the decrease of the overloading effect of ammonia resulting from bacterial activities in the intestine, has a beneficial effect on the healing process in liver surgery.