Acid-base disturbances were examined during experimentally induced infection in the rabbit with Eimeria stiedai, a parasite that profoundly modifies liver morphology and physiology, resulting in anatomical and functional alterations similar to those appearing in different human hepatic diseases. Over 28 days of infection, bicarbonate and lactate concentrations, partial pressures of O2 and CO2, and pH values were determined in the blood and bile of infected animals and compared with the values obtained in noninfected rabbits. The plasma activity of several liver-indicator enzymes was also evaluated. Under our experimental conditions we observed an uncompensated metabolic acidosis that developed with elevated levels of lactate and reduced concentrations of bicarbonate in blood and bile and tended to be compensated by respiratory and biliary mechanisms.