Although water deficiency has been seriously taken up as a subject in reducing crop production in arid and semi–arid areas, nevertheless little information has been published regarding its effects on seed quality. To evaluate the effects of irrigation regimes (full irrigation (control), irrigation until flowering stage, irrigation until doughing stage and irrigation until eight-leaf stage) on grain yield, yield components and some germination attributes in grain sorghum (Sorghum bicolor L. CV. Kimia), experiments were conducted at research farm and laboratory of Agricultural College, University of Tehran, Karaj, Iran in 2005. The experiments were arranged with a Randomized Complete Block Design (RCBD) and Completely Randomized Design (CRD) with four replications in farm and laboratory, respectively. The results idicated that irrigation levels had significant effects on grain yield and yield components
(p<0.01). Control plants had more grain yield and yield components than the other irrigation levels due to the longer growth season and better use of environmental conditions. Withholding irrigation at eight-leaf stage decreased grain yield and its components. Nevertheless, qualitative attributes i.e. germination percentage, germination rate and seed vigor index were not significantly affected by irrigation levels. Thus, it doesn't seem that water deficiency would have a direct effect on metabolic activity of seed and consequently on seed quality. However, the foregoing treatments exhibited negative effects on seed yield.