Hepatic encephalopathy is characterized by a number of neuropsychiatric and motor disturbances observed in patients with liver dysfunction. The purpose of this study is to fully characterize behavioral and physiological sex differences in an animal model of fulminant hepatic encephalopathy (FHE). Male and female rats were administered thioacetamide (600 mg/kg) via i.p. (intraperitoneal) injection at Hours 0 and 24 and allowed to progress into the four stages of FHE. Male rats reached all four stages of FHE significantly earlier than female rats (p < 0.05). The performance of the male rats deteriorated more quickly (p < 0.05) than that of the females in all of the sensory and motor behavioral tests. Sex differences were observed in the liver enzymes of the FHE rats. The levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase were significantly greater (p < 0.05) in male rats in all four stages of FHE. Significant increases were also observed in the levels of direct and total bilirubin (p < 0.05). Neuronal damage was observed in the CA1 and CA2 regions of the hippocampus. In the CA1 region, male rats displayed greater pathological changes in Stages III and IV (p < 0.05) than female rats. The damage in the CA2 region was only observed in Stage IV male rats. Our data indicate that observable behavioral and physiological sex differences occur in thioacetamide-induced FHE in the rat.