Source and sink relationship determine the growth and development in cereals, and can serve as reliable indicator to estimate durum wheat yield. A multi-year field trial was executed on ICARDA farm, Sids Agricultural Research Station farm, Agricultural Research Center (ARC), Egypt, during the two successive growing seasons of 2018/2019 and 2019/2020 to determine the effect of defoliation (source and sink limitation) on the yield attributes and grain yield of eight durum wheat cultivars. Eight defoliation treatments viz., i) control (no defoliation), ii) flag leaf blade removed, iii) flag leaf blade and the secondary leaf removed, iv) secondary leaf removed, v) spike awns and secondary leaf removed, vi) spike awns and flag leaf blade removed, VII) spike awns removed, and viii) Spike awns, flag leaf blade and secondary leaf removed were applied on eight durum wheat cultivars viz. i) Bani Suef 1, ii) Bani Suef 3, iii) Bani Suef 4, iv) Bani Suef 5, v) Bani Suef 6, vi) Sohag 3, vii) Sohag 4 and viii) Sohag 5. The study was comprised of wheat cultivars as the main plot while, defoliation (source and sink limitation) treatments as the sub-plots. Cultivars and treatments had significant effect on the number of grains spike-1, 1000-grain weight and grain yield. However, the highest grain yield was obtained from ‘Bani-suef-1under all wheat defoliation treatment. On the other hand, the removal of spike awns and the secondary leaf treatment produced the highest 1000-grain weight and grain yield.