I examined the pattern of mortality in the Donner Party, a group of emigrants who became trapped with inadequate food stores in the winter snows of the Sierra Nevada mountains in 1846-1847. The party consisted of 90 persons; the median age was 19.5 years (range, 1 to 70), 55 (61%) were male, and 72 (80%) were traveling with family members. Of the 90 persons, 42 (47%) died. Multivariate regression analysis indicated that age was the most important mortality risk factor. The lowest mortality (10%) was seen in the 6- to 14-year age group, and the highest was for persons younger than 6 years (relative risk = 6.6; 95% confidence interval [CI], 2.3 to 9.6) and persons 35 years or older (relative risk = 8.4; 95% CI, 3.4 to 10.2). Persons traveling without other family members had a relative risk of 2.0 (95% CI, 1.0 to 2.5). Men and boys were also at increased risk (relative risk = 2.0; 95% CI, 1.0 to 2.9). These factors can identify persons at increased risk for mortality in nutritionally stressed populations, and efforts to maintain intact family structures may improve survival.