AbstractTwo groups of patients suffering from Senile Dementia of the Alzheimer Type (S.D.A.T.) have been studied from first referral till death in hospital. The point of separation between the two groups was age — the younger group were aged 65–74 at the time of terminal admission and the older over 85.The variables studied were history of illness prior to referral, assessment on the Crichton Royal Behavioural Rating Scale at the time of terminal admission, duration of illness and duration of hospital stay. The last two factors were measured both in absolute terms and as features relative to life expectancy.The history proved unhelpful in identifying features capable of separating the two groups. Although in absolute terms the younger group survived longer, both from onset of illness and admission, in relative terms these patients fared considerably worse.The possibility that S.D.A.T. in the very elderly runs a more benign course is discus