Investigation on the effect of stem damage by Scirpophaga incertulas (Wlk.) the yellow stem borer on yield contributing characters of 27 deep water rice cultivars indicated that the percent reduction in panicle length, number of grains panicle^-1, 1000 grain weight and increase in the chaffy grain percent varied between 8.21 - 16.42, 7.83 - 16.99, 9.09 - 22.57 and 8.8 - 16.5 percent, respectively in plants with stem damage over the healthy ones. Percent reduction in the indices of various yield contributing characters was at higher levels in LPR-56-49, IR-4547-212, TC-6 and Bengdang Kumini. Percent yield reduction (PYR) was lowest in NDGR - 398 followed by NDGR-410, Jalnidhi, NDGR-421, Kariawa and TCA – 4, whereas yield reduction index (YRI) and percent yield loss due to stem damage were lowest in NDGR-398 followed by TCA-4, Jalanidhi, Kariawa, NDGR-410, NDGR-421 and in the higher range in Bengdang Kumini, LPR-5649 and IR-5533-56-1-12 and the highest in susceptible check Jalamagna. The percent yield loss due to 1% damaged stem varied between 0.224 - 0.438 with an average of 0.31 as compared with 0.50 in the susceptible check Jalamagna.