Plants of small-seeded lentil plants (cv. Obrazcov) and that of coarse-seeded (cv. Izka) were subjected to soil drought in pot experiment in three developmental phases: 1) second offshoot — vegetative phase, 2) full blooming, 3) advanced development of pods, and its direct and consequent effect on the growth of plant height, of the dry weight of shoots and roots, and on seed-yield structure components were determined. The seed yield was most strongly limited after drought during blooming phase, especially in cultivar Izka, to less extent — after drought in vegetative phase, but in the phase of advanced pod development it did not cause any significant effects. The results obtained show that the response of compared lentil cultivars is differentiated and that the more significant reduction of seed yield is caused by drought in the blooming phase.