The aim of this study was to examine the toxicity of organophosphorus insecticide Dichlorvos in wild pigeons (Rockdov), and measuring cholinesterase (ChE) activity in the serum, plasma, brain, liver and Pectoralis muscle using a modified electrometric method.The maximum activity of ChE was in the serum (1.03 ∆pH/30 min) and the minimum ChE activity in liver (0.04 ∆pH / 30 min) as well as inhibition effect of Dichlorvos on ChE activities in serum, plasma, brain, liver and Pectoralis muscle. Whereas the maximum inhibition appear in plasma 88-95% in the pigeons that treated by (10-20 mg /kg B.W) of Dichlorvos. The oral median lethal dose (LD50) of Dichlorvos in pigeons is 21.4 mg/kg B.W. Atropine at 20 mg / kg S.C lead to decrees in toxicity signs in the pigeons that treated by 20
mg /kg B.W of Dichlorvos orally, decrease of death 33 % and delay time of death. Where as pigeons treated by atropine at 20 mg / kg and diazepam 5mg/kg subcutaneously was effective in reducing toxicity signs and 100 % protected the birds that treated by Dichlorvos from death.