Drought and high temperature are two major factors limiting crop production. The two stresses occur together in many regions of the world but they usually are investigated separately. Irrespective of the genotype, growth or treatment conditions, grain growth was severely reduced when wheat plants were exposed to high temperature, drought and combination of both the stresses during endosperm cell division. The extent of thermal as well as drought induced disruption of grain development, however was dependent on genotype. This structural data support the hypothesis that high temperature and drought during endosperm cell division reduces grain sink potential and subsequently mature grain mass, mainly by disrupting cell divisions in peripheral and central endosperm and thus reducing endosperm length and breadth to a considerable extent. The interaction of high temperature and drought stresses resulted in stronger reduction of pericarp thickness and endosperm size than either stress alone.