Mood assessments were made after six months of 149 survivors taken from a register of all patients admitted to hospital with acute stroke. Using a General Health Questionnaire score of 12 or more as a criterion of important affective illness, its prevalence was 23%. There was no difference in risk of affective illness between left and right hemisphere strokes. Affective illness was strongly associated with functional ability, with limb weakness and with longer hospital stay in those with good functional recovery. Only 15% of those with high scores were receiving antidepressant drugs. The general practitioner is in the best position to detect psychiatric illness in stroke survivors; the use of mood rating scales such as the GHQ, in conjunction with clinical assessment, may improve detection.