An Interventional and field trial study carried out in the siaho area, (Bandar Abbas, Iran) during 1994 to 1995. Efficacy of Deltamethrin - Impregnated was compared to that of untreated and treated villages, in relation Malaria control. 6 villages with a total population of 4421 and 2 villages with a total population of Deltamethrin - Impregnated bed net was compared to that of untreated and treated villages, in relation Malaria control. 6 villages with a total population of 4421 and 2 villages with a total population of 1825 were used as treatment and control, respectively.The collection, impregnation (target dosage of 25 mg active ingredient [AI] / m2), redistribution of the nylon nets, carried out in early April, Were done by local health workers, supervised by the senior research staff.Species composition of Anopheline catches in different methods in control and treated villages was Anopheles dthali 33.8% Anopheles stephensi 39.6%, 41% Anopheles culicificies 3.3% , 2.5% Anopheles superpicuts 3.9% , 4% Anopheles, thurkhudi 4.2% , 3.6% Anopheles moghulensis 4.8% , 4.9% Anopheles fiuvatilis 10.3% 15.3% , respectively.The use of impregnated bednets has significant effect on the inicidence of Malaria and positive slide but no significance effect was observed in human and animal blood behavior and indoor resting density of vectors. The mortality of anophelines brought in contact with the treated nets for 3 min. in bioassay dropped to less than 90% in 5 months. In south of Iran with different vectors, exophilic and endophagic habit, long transmission season, the use of impregnated bednet with pyrethroid insecticides with other integrated control measures and residual spraying should be used.