Background: Delirium is a common condition in the early stages of acute stroke. We conducted a systematic review to evaluate incidence, risk factors and outcome in patients that evolve delirium during the first two weeks after acute stroke. Method: We did an updated search for relevant articles in PubMed and EMBASE published between January 2011 and August 2016. For older studies, we used the studies included in two systematic reviews published in 2012. Results of interest were incidence of delirium in acute stroke, associated risk factors and prognosis. Results: 5 studies published after 2011 met the inclusion criteria. In total 28 studies were included. Incidence ranged from 2,3 % to 66 %, with a great variety in diagnostic procedures. The main emphasis of reported incidence was found between 10 – 30 %. Higher age, medical complications and pre-stroke cognitive decline were associated with the development of delirium. Risk factors more specific to acute stroke were stroke severity, total anterior circulation infarct and right hemispheric lesion. 14 studies reported outcome, of which length of hospital stay was found up to be more than 100 % longer in stroke patients with delirium. They also were more likely to be institutionalized and have worse functional outcome both at discharge and after 1 year. Patients with delirium were more likely to die during hospitalization. Conclusion: In acute stroke, delirium is a common and severe complication that requires early recognition and treatment. Delirium is associated with a number of risk factors, and predict poorer outcome both short and long term.