AbstractDespite being a cardinal experimental model, the induction of cirrhosis in rats by repeated exposure to carbon tetrachloride (CCl4) has low reproducibility. Here, we compared two models of cirrhosis induced by orogastric administration of CCl4 once (CCl4-1xWk) or twice a week (CCl4-2xWk) for 12 weeks in male Sprague-Dawley rats. Control rats received water instead of CCl4. Both CCl4 protocols similarly attenuated body weight gain (p < 0.01 vs. Control). Although both CCl4 protocols increased hepatic fibrosis, portal hypertension and splenomegaly, the magnitude of these alterations was higher and more consistent in CCl4-2xWk rats. Importantly, two CCl4-1xWk rats did not develop cirrhosis versus a 100% yield of cirrhosis in CCl4-2xWk rats. The CCl4-2xWk protocol consistently induced liver atrophy together with hematological, biochemical and coagulation abnormalities characteristic of advanced cirrhosis that were absent in CCl4-1xWk rats. Ascites occurred in 20% and 80% of rats in theCCl4-1xWk and CCl4-2xWk groups (p < 0.01). All rats showed normal renal function, arterial blood gases and stable systemic hemodynamics. The total dose of CCl4 and mortality rate were similar in both protocols. The CCl4-2xWk protocol, therefore, was highly reproducible and effective for the induction of experimental cirrhosis within a confined time, representing a valuable advance for liver research.