In prelude of implementing IRS in the Baroueli district through PMI/USAID’s support, entomologic baseline studies were conducted. Mosquitoes were collected monthly using pyrethrum spray catches and human landing catches from June to October 2010. Bioassays were conducted to assess insecticide resistance in vectors using WHO kits. The collections comprised 81.2% of Anopheles spp, 18% of Culex spp and 0.8% of Aedes spp (n=11583). Anopheles gambiae s.l. represented 80% of the Anophelines (n=9402). Within An. gambiae s.l., An. coluzzii represented 83.2% of the total collection (N=1403) against 10.8% for An. arabiensis and 6.0% for An. gambiae. EIRs by PCS were 0, 2.3, 7.8, 5.8 and 1.4 infective bites per human per month from June to October, respectively. By HLCs EIRs were 0, 5.3, 28.5, 19.1 and 0. The numbers of mosquitoes collected indoors (98.7, SD=109.9) and outdoor (85.8, SD=106.2) were comparable (independent T-test, p=0.856). Bioassays showed resistance to pyrethroids and DDT while bendiocarb showed high efficiency (100% mortality) which led the National Malaria Control Programme to shifting from pyrethroids to bendiocarb for IRS. These results indicate that malaria transmission might be considerable outdoor as well as indoors and that the major malaria vector is resistant to pyrethroids but susceptible to carbamates.