The overall purpose of this work is to throw some light on the acute oral toxic effects of three commercial formulations of chlorpyrifos (i.e. Dursban, Pyriban and Chlorzan) 48% E.C. and cypermethrin (Sparkil 25% E.C.) and the mixture of Dursban and Sparkil on adult male and female albino rats. All the tested formulations were administered in corn oil to the rats and the median lethal doses (LD₅₀ values) were determined after 24, 48, 72 and 96 hours (hrs) of treatment. The obtained results revealed that the oral LD₅₀ values of the tested insecticide formulations (Dursban, Pyriban, Chlorzan and Sparkil) on adult male and female rats were (125, 115), (100, 94), (140, 103) and (387, 251) mg/Kg body weight (b.w.) after 24 hrs, respectively. The 48hrs oral LD₅₀ values of the fore mentioned formulations were (112, 90), (100, 75), (126, 81) and (230, 206) mg/Kg b.w., respectively. On the other hand, the acute oral toxicity of the mixture of  Dursban and Sparkil was considerably higher than the acute toxicity of each of them since the acute oral LD₅₀ values were 102 and 75 mg/Kg b.w. for male and female rats after 24hrs, respectively.