||Grain set failure or sterility in wheat is an important yield constraint in the rice-wheat system of South and Southeast Asian countries including Bangladesh occurring in some years but not in others. Wheat sterility was first observed in Brazil in 1962 (Da Silva and Da Andrade, 1980). Widespread sterility was observed in Nepal in 1964 when improved and high yielding wheat cultivars were introduced (Misra et al., 1992). Li et al. (1978) published the first report of large-scale wheat sterility describing 40,000 ha of wheat in Heilongjiang Province in North China. In Bangladesh sterility was first noticed in the Mexican wheat variety, Tanori 71 in the Thakurgaon seed increase farm of .the Bangladesh Agricultural development Corporation in the mid seventies (Saifuzzaman and Meisner, 1995). Since then, spikelet sterility has been observed sporadically in different areas of Bangladesh. In 1987 and 1988, spike sterility in farmers' fields was reported from two northern districts, Rangpur and Dinajpur. Soil analysis indicated low boron levels with almost all the varieties in the affected plots showing sterility to some extent. The percentage of sterility was 84, 82, 75, 24 and 12% in Kanchan, Akbar, Ananda, Barkat and Sonalika, respectively (Sufi and Meisner, 1996). Again sterility was observed in 1998-99 in Pakistaniand Indian-origin wheat varieties Inquilab and Raj-3027, respectively, specifically in greater Rangpur and Dinajpur districts. Survey results indicated that grains/spike were 0 in high sterility fields compared to 48.8 in non-sterility fields, while 0 and 2.43 were the lowest and highest grains/spikelet in surveyed wheat fields. Sterility percentage ranged from 27% to 100%. The survey results indicated that where sterility does occur, it severely decreases the crop yields. This phenomenon is a common occurrence in rice-wheat system areas of the South Asian countries and needs much attention to establish wheat and sustain production in non-traditional wheat growing areas.