Downy mildew (DM) caused by the Peronosclerospora maydis is considered the most damaging disease of maize (Zea mays L.) in South Asia. In East-Timor, it has been widely spread and considered as the major stress of maize production. It was observed at Loes Research Station and farmers’ field since 2004. All materials exhibited high susceptibility to DM infection at the CIMMYT trial. Only Suwan5 (Thailand), LYDMR (CIMMYT) and Arjuna (Indonesia) showed tolerance. Different trials with 900 crosses were tested at 5 locations; Lospalos, Dili, Comoro, Aileu and Loes in 2006/2007 In 2008, high DM infection was observed at Loes. Crosses of Suwan5, NAI, Arjuna and DMR-ESR-Y (IITA)with tropical and temperate germplasm showed tolerance. The International Corn Foundation (ICF)/KNU team with the Ministry of Agriculture have run breeding research three cycles yearly. By 2007, the joint team developed an open-pollinated variety (OPV) with combined tolerance to DM and drought. The Ministry named it "NAI", means "honorable" in national language. Hybrid breeding for both DM and drought are being developed.