A curvilinear relationship between grain yield and leaf area was found. Generally, changes in each of the 3 yield components were responsible for yield differences, although number of seeds per head and seed weight underwent greatest change. Greater yield reduction resulted from removing leaf area from upper than from lower portions of the plant. Likewise, removing alternate leaves was more deleterious than removing half of each leaf. In 1959, mean yield decreases of 23, 35, 43, and 95%, respectively, were obtained from removing approximately 33, 50, 67, and 100% of the leaf area at late boot and anthesis stages.