Abstract: Field experiment involving six cultivar-mixed combinations from seven wheat cultivars (“Fan19”, “Yin11-12”, “Chuanmai107”, “Jingmai10”, “Qingchun55”, “46548-3” and “An96-8”) was conducted in a multi-site setting from 2003 ~ 2006 in Qujing, Yunnan Province to evaluate the effects of mixed planting of different wheat cultivars on yield and stripe rust severity under natural disease conditions. Overall, the effect of cultivar mixture on yield is +3.9%. The frequencies of positive, neutral and negative effects on yield are 69.4%, 8.3% and 22.3% respectively. Individual environmental conditions like site location and year affect cultivar mixture effect on yield. In years when stripe rust is relatively severe, all mixed combinations reduce disease index of stripe rust. Thus using cultivar mixtures can have practical implications for wheat production in China.