BACKGROUND: The purpose of this study was to analyze and determine the prevalence and clinical characteristics of hospitalized dementia patients compared with nondemented patients. METHODS: We examined hospital discharge database records dated 1998-2003 from public hospitals in Andalusia, Spain. We used ICD-9-CM codes to identify patients with dementia. The variables examined included age, length of stay, discharge diagnosis, diagnostic-related groups, and mortality of both dementia and nondementia patients over 65 years of age. RESULTS: A diagnosis of dementia was documented for 40,482 cases. The prevalence of dementia increased from 3.43% to 4.64% between 1998 and 2003 and was higher among older patients and women. Dementia was the reason for admission in 5.6% of cases. Medical reasons constituted 82.4% of admittances. Dementia patients had hip surgery more frequently than patients without dementia, and other procedures (orthopedic surgery, cataracts, or hernia repair) were less frequent (p < 0.001). The mean duration of the hospital stay was longer (13.4 vs. 10.7 days) and the intra-hospital mortality rate was greater (19.3% vs. 8.7%) for patients with dementia compared to those without dementia. Dementia was an independent predictor of mortality (OR 1.77; 95% CI 1.72-1.82). CONCLUSIONS: Dementia is increasing among hospitalized patients. Dementia patients have different reasons for hospitalization and higher mortality. It is necessary to identify these differences and to improve the hospital care of dementia patients.