Background and Purpose-The goal of the present study was to examine a series of putative risk factors of poststroke dementia (PSD), especially those factors usually associated with cerebrovascular disease and degenerative dementia, in a series of 251 consecutive unselected stroke patients. Methods-A standard protocol was prospectively applied at admission and 3 months after stroke; this protocol included clinical, functional, and cognitive assessments, hemogram and serum biochemistry, ECG and CT exams, apolipoprotein E and angiotensin-converting enzyme genotype, and neuropsychological examination. After a neuropsychological examination and an interview with a relative, the following diagnostic criteria were used: the Diagnostic and Statistical Manual of Mental Disorders (DSM)-IV for dementia after stroke, DSM-III-R for previous dementia and dementia stage, and Association Internationale pour la Recherche et l'Enseignement en Neurologie (NINDS-AIREN) for vascular dementia. Results-Seventy-five cases (30%) demonstrated dementia at 3-month follow up; 25 of them (10%) had demonstrated dementia before the stroke. Dementia was unrelated to type (ischemic/hemorrhagic) or location of stroke, vascular factors (hypertension, diabetes, ischemic heart disease, or hypercholesterolemia), apolipoprotein E or angiotensinconverting enzyme genotype, and serum homocysteine. Age (odds ratio [OR] 1.1, 95% CI 1.03 to 1.2), previous nephropathy (OR 6.1, 95% CI 1.5 to 24.3), atrial fibrillation (OR 4.4, 95% CI 1.4 to 13.9), low Canadian Neurological Scale score at discharge (OR 0.5, 95% CI 0.4 to 0.6), and previous mental decline assessed by the shortened Spanish version of the Informant Questionnaire on Cognitive Decline in the Elderly (SS-IQCODE; OR 1.2, 95% CI 1.1 to 1.4) were the correlates of dementia in logistic regression analyses. The same risks factors were found when cases with previous dementia and with hemorrhagic stroke were excluded. Conclusions-Dementia is frequent after ischemic or hemorrhagic stroke. Age, nephropathy, atrial fibrillation, previous mental decline, and stroke severity independently contribute to the risk.