Although clinical observations suggest that some patients experience hunger and food insecurity, there are limited data on the prevalence of hunger in adult patients. To determine the prevalence of hunger and food insecurity in adult patients at an urban county hospital. Cross-sectional survey conducted in 1997. The primary survey included all patients aged 18 years or older who were admitted to the medicine, surgery, and neurology services during a 2-week period, and all patients who attended the hospital's general medicine clinic during 1 week. A second survey included primary care patients who received insulin from the hospital pharmacy during a 1-month period. Rates of hunger and food insecurity. Of 709 eligible patients, 567 (participation rate, 80%) were interviewed in either the clinic (n=281) or hospital (n=286). An additional 170 patients who received insulin were interviewed by telephone (response rate, 75%). Of the primary sample, 68 (12%) respondents reported not having enough food, 75 (13%) reported not eating for an entire day, and 77 (14%) reported going hungry but not eating because they could not afford food. A total of 222 (40%) had received food stamps in the previous year and of those, 113 (50%) had their food stamps reduced or eliminated. Recipients whose food stamps had been eliminated or reduced were more likely to report not having enough food (18% vs 13%, P=.006), not eating for a whole day (20% vs 16%, P=.01), going hungry but not eating (20% vs 16%, P=.08), and cutting down on the size of meals or skipping meals (33% vs 27%, P=.01). In multivariate analysis, independent predictors of hunger included an annual income of less than $10000 (odds ratio OR, 7.55; 95% CI, 3.01-18.92), drug use (OR, 3.56; 95% CI, 1.46-8.66), and a reduction in food stamp benefits (OR, 1.73; 95% CI, 1.01-2.96). Predictors of food insecurity included an annual income of less than $10000 (OR, 4.12; 95% confidence interval CI, 1.98-8.58), drug use (OR, 2.11; 95% CI, 1.66-5.08), and a reduction in food stamps (OR, 2.02; 95% CI, 1.23-3.32). In addition, 103 (61%) patients in the sample of diabetics reported hypoglycemic reactions; 32 (31%) of these were attributed to inability to afford food. Hunger and food insecurity are common among patients seeking care at an urban county hospital.