Weight loss is a common problem in patients with Alzheimer's Disease (AD). It is a predictive factor of mortality and it decreases patients' and caregivers' quality of life. To determine if a nutritional education program can prevent weight loss in AD patients. 151 AD patients and their caregivers were enrolled to follow the intervention and 74 AD patients and their caregivers constituted a control group. Caregivers in the intervention group followed 9 nutritional sessions of one hour each, over one year. Caregivers in the control group didn't follow any sessions but were offered advice provided in a normal follow-up. Patients weight, nutritional state, cognitive function, autonomy, mood, behaviour disorders at baseline and at 6- and 12-month follow-up. Caregivers burden, nutritional and AD knowledge at the baseline and at the 12-month follow-up. During the year follow-up, the mean weight increased in the intervention group (0.7+/-3.6 kg) whereas it decreased in the control group (-0.7+/-5.4 kg) (p<0.05). The nutritional status (MNA) was maintained in the intervention group (0.3+/-2.6) whereas it decreased significantly in the control group (-1.0+/-3.4) (p<0.005). After adjustment for baseline differences between the two groups (caregiver age, nutritional state, eating behaviour disorders, depression), the weight change between the two groups was not significant (0.6+/-0.4 kg vs. -0.6+/-0. 6 kg respectively in intervention group and control group). However, the percentage of patients with significant weight loss is decreased. The MMSE change became significant between the two groups: -2.3+/-0.3 vs. -3.4+/-0.4 respectively in intervention group and control group (p<0.05). These results suggest that a nutritional educational program intended for caregivers of AD patients could have a positive effect on patients weight and cognitive function.