The aim of the study was to determine duration of delirium in patients with acute stroke according to sex, age, type and localization of lesion. We assessed delirium prospectively in a sample of 233 consecutive patients with an acute (< or =4 days) stroke using the Delirium Rating Scale (DRS-R-98) and Diagnostic and Statistical Manual of Mental Disorders (DSM IV). The average duration of delirium was 4 days in patients with ischemic stroke and 3 days in patients with hemorrhagic stroke. There was no statistically significant difference in delirium duration between these two patient groups. A longer duration of delirium was recorded in women and in patients older than 65. The period of delirium was longer in patients with right hemispheric lesions. Patients did not differ according to delirium duration, sex, age, type and localization of stroke. In two thirds of patients, the symptoms of delirium completely disappeared on medicamentous treatment, while in the remaining one third of patients certain symptoms of delirium persisted at discharge (p=0.003). Mortality rate was significantly higher in patients with delirium in the acute phase of stroke than in those without delirium (p=0.009). In conclusion, delirium is a temporary manifestation in two thirds of patients in the acute phase of stroke. Patient sex and age, and type and stroke localization have no influence on delirium duration.