Mortality associated with diarrhea was investigated in a longitudinally followed cohort of children under 6 years of age in rural North India. During the followup, 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 1 and 2 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.