Abstract: The acute toxicity study of methanolic extract of Smilax kraussiana leaves was investigated in rats. The parameters studied were the liver enzymes (transaminases), cholesterol, protein, creatinine and urea serum levels as well as the ionic analysis. Both alanine aminotransferase (ALT) and Aspartate aminotransferase (AST) showed a significant (p<0.01-0.001) non dose-dependent decreases in serum levels. There were also non dose dependent decreases in cholesterol, protein and creatinine serum levels (p<0.001). The serum level of urea did not indicate a significant change. Sodium and chloride ions showed discriminatory rise in serum levels especially in high doses (p<0.05-0.001) while the potassium serum level remained statistically insignificant. The physical signs of toxicity ranged from decreased motor activity with loss of appetite to increased respiratory rate, restlessness, gasping and death. The median lethal dose was calculated to be (240.00±49.44 mg kg-1). The extract may in part possess some antihepatotoxic effects.