The study aimed to test the effect of cumulative dose of BHT and Nigella sativa oil on the liver and kidney of rats. Rats were orally exposed to BHT (500mg/kg), oil (0.5 ml/rat), and a combination of the obvois doses for two weeks. The results indicate that the oral toxicity of BHT or Nigella staiva oil in rats is of lower order, but this toxicity was increased when the rats treated with the comination of BHT and Nigella sativa oil.