Mortality associated with diarrhea was investigated in a longitudinally followed cohort of children under six years of age in rural North India. During the follow-up, 1663 episodes of diarrhea and 23 diarrhea related deaths were recorded in 1467 children followed up for 20 months. The case fatality rate was 0.56% for acute watery diarrhea, 4.27% for dysentery and 11.94% for non-dysenteric persistent diarrhea. Most of the episodes lasted less than a week; 5.2% became persistent (duration > 14 days). The case fatality rate was similar in episodes of one and two weeks' duration (0.64% and 0.8%) and increased to 13.95% for persistent episodes. Of the total 86 persistent episodes, 22.1% were dysenteric; the case fatality rate for such dysenteric persistent episodes was 21.1% and for watery persistent diarrhea 11.4%. Diarrheal attack rates were similar among different nutritional groups, but diarrheal case fatality rates progressively increased with increasing severity of malnutrition, these were 24 times higher in children with severe malnutrition (7.48%) compared to those normally nourished (0.31%). With availability and use of oral rehydration therapy, dysentery and persistent diarrhea emerge as major causes of diarrhea related mortality, with underlying malnutrition as a key associated factor.