Primary and secondary prevention strategies for Alzheimers disease (AD) are urgently needed. We have initiated a five-year prospective prevention study involving patients spontaneously reporting memory complaints. The primary objective is to determine the effect of treatment with EGb 761® on the rate of conversion from memory complaints to AD using survival analysis. Ambulatory patients aged at least 70 years who spontaneously reported a memory complaint during a GP or memory centre consultation were eligible for inclusion. Patients with major objective memory impairment or clinically relevant symptoms of anxiety and depression were excluded. Subjects were randomised to receive either EGb 761 120mg bid or matching placebo. Participants undergo an annual visit at a memory centre, where a series of neuropsychological tests are administered to assess cognitive function (Grober and Buschke, Trail-Making and controlled oral word association tests) and cognitive status (MMS and CDR). Functional status is evaluated with the Instrumental Activities of Daily Living questionnaire. The primary outcome is the transition to a diagnosis of AD (DSM-IV and NINCDSADRDA criteria), determined at the annual memory centre visit. A total of 4066 patients were screened for participation, of whom 2854 fulfilled the eligibility criteria and were entered into the study. Their mean age was 76.8±4.4 years and 66.7% were female. The mean MMSE score was 27.8±1.7 and 55.5% presented a CDR score of 0.5. This study will enable us to evaluate the efficacy of EGb761 in the prevention of AD, and to assess the usefulness of various baseline characteristics as predictors of conversion to AD in this population.