Cognitive ability was assessed in a consecutive series of 189 six-month survivors of an acute stroke. Twenty-two patients were cognitively impaired at six months. Amongst 10 patients whose cognitive ability deteriorated between one and six months, four also had marked depressive symptoms. Age and severity of stroke were the factors most strongly associated with cognitive impairment at six months. Patients with left hemisphere damage had significantly more difficulty with short-term recall and those with bilateral hemisphere signs were most at risk of cognitive impairment. Patients with cognitive impairment after a stroke should be carefully assessed for depressed mood which may benefit from treatment.