Abstract: To estimate the toxicity according to simple chemical is not helpful when severa materials bave??en taken in the forensis cases. The purpose of this tudy is to investigate the effects of the interaction of alcohol + DDVP, alcohol +trichlorfon, alcohol+methamicophos and alcohol+dimethoate in mouse. As a results: the LD50 of alcohol, DDVP, trichlorfon,methamidophos and imethoate were 9501, 71.97, 441. 2, 10.00 and 182.8mg/kg respectively.For the alcohol + DDVP, alcohol + trichlorfon,alcohol+methamidophos and alcohol+ dimethoate the LD50 measured were 5044, 5622, 3281 and 8281 mg/kg and the LD50 expected were 909.1, 5000, 5000 and 5000 mg/kg, hence the ratio of them (LD50 expected/LD50 measured) were 0.1802, 0.8894, 1.5239 and 0.6038 respectively. It is concluded that there is an antagonistical effect of interaction for alcohol+DDVP and an additive effect of interaction for alcohol+trichlorfon,alcohol+methamidophos and alcohol+dimethoate.