 The trial is designed as a patient-blinded, single-center, randomized, controlled, parallel group, phase I clinical study of repeated once every 4 weeks administration by subcutaneous injection of AFFITOPE AD02 alone or adsorbed to aluminium hydroxide in 24 patients with mild to moderate Alzheimers Disease. In total, each patient will receive 4 immunizations. Patients will be randomized to receive AFFITOPE AD02 alone or adsorbed to alumimium hydroxide. Each treatment group consists of 12 patients. For safety reasons, inclusion of patients will be done in a stepwise manner. 