A comparative survey of feeding habits and food intake was undertaken in 16 farm families resident in Nong Kohn, a small Lao-Thai village in which bladder stone is endemic and in 15 families, predominantly shopkeepers and government workers, in Ubol, a municipality (pop. 27,000) with a 14-fold lower prevalence of the disease. Studies were conducted in March (hot season), August (rainy season), and November (cool, dry season) in the 2 sites, 16 km apart. Differences in foods consumed are discussed. Caloric intakes calculated per capita for the groups (which were similar but not identical in age and sex composition) were similar and adequate by United States standards. Greater consumption of rice in the village compensated for the smaller quantities of other foods consumed. Village fat intakes were extremely low; 70% of protein consumed was of vegetable origin as compared to 56% in Ubol. Calcium and P intakes were higher in village diets, attributed to the higher consumption of fermented whole fish. Vitamin A intakes in village diets were one-third and vitamin C one-half those of town families; intakes in both groups were below United States standards for these nutrients. Fairly marked increases in vitamin A and C intakes occurred in the rainy season sample of village diets; seasonal differences in intakes in town families were not marked. Significant differences in age of introduction to solid foods were noted. It was estimated that rice supplement contributed 170-220 cal/day in 16 village infants less than 30 days old. Although the nutritional consequences of such feeding practices were not measured, it appeared probable that rice feedings significantly lower daily breast milk consumption as well as fluid intake. Body weights of Nong Kohn infants were lower than equivalent age Ubol, Bangkok, or Boston, Massachusetts infants, suggesting that the former infants were relatively protein deficient. Neonatal protein deficiency may be etiologically related to development of urinary tract stones in humans, as has been demonstrated in rats.