The toxicity of acetaminophen taking in toxic doses per body weight of 12 adult rats, over a period of 12 days, allowed the biochemical and histological evaluation of the intoxication risks over time. The twelve rats, male and female of 100 grams as average weight, were divided into four groups (of three rats each), were exposed to different increasing doses of acetaminophen 200, 800, 1400 and 2000 mg/kg. The hepatic cytolysis and the congestion of the renal parenchyma were observed in all rats. Biochemically, since the first four days, there was an increase of AST noted with high doses of acetaminophen, and a discrete elevation of creatinine. Tracking -histologically- the toxicity over time shows that renal congestion regresses despite the continuation of toxicity. Contrary, in the liver, cytolysis shows no regression during the time of the experiment. This study allows to highlight some acetaminophen intoxication risks. These risks seem higher than what is commonly admitted.