BACKGROUND: Controversial findings are reported on hospital outcome in cognitively impaired patients. The aim of this study was to explore mortality risk according to cognitive status during hospitalization and after 3 months in elderly patients. METHODS: Sixty-six internal medicine and geriatric wards in Italy participated in the "Registry Politerapie SIMI (REPOSI)" during 2010. Of the 1,380 in-patients, aged 65 and older enrolled, 1,201 were included. Cognition was evaluated with the Short Blessed Test (SBT). Logistic regression was used to evaluate the association of questionable and impaired cognition (according to SBT cutoff points) with mortality during hospitalization and at follow-up. Morbidity, function, and adverse events during hospitalization were covariates. RESULTS: Four hundred and twenty-one participants were classified as normal, 219 questionable, and 561 cognitively impaired. Forty-nine patients died during hospitalization and 70 during follow-up. Sixty-seven point three percent versus 32.7% (p < .001) of patients who died during hospitalization and 54.3% versus 45.7% (p < .001) during follow-up had at least one adverse event. After multiadjustment, impaired cognition was associated with in-hospital mortality (odds ratio [OR] = 3.1; 95% confidence interval [CI] = 1.1-8.6) but not with mortality at follow-up. Increase severity of cognitive impairment was associated with higher odds of mortality (from 2.7 in those with moderate impairment to 4.2 in those with severe impairment). After stratification for adverse clinical events, impaired cognition resulted associated with mortality only in patients having at least one event. CONCLUSION: Elderly patients with cognitive impairment are more likely to die during hospitalization with a severity-dependent association. Adverse events may represent an important target of prevention due to their high association with mortality and cognitive impairment.