Background The purpose of the study was to determine the eating habits of patients with MCI or AD and to determine their nutritional status. Methods patients with MCI or AD were recruited in the dementia outpatient clinic. Cognitive status and nutritional status were evaluated. Each patient or his/her caregiver fill out full Mini Nutritional Assessment scale (MNA). Maximal score on MNA was 30, patients at risk of malnutrition scored between 17 and 23.5. Patients with less than 17 were considered malnourished. Descriptive statistic for age, body mass index (BMI), arm/calf circumference and total MNA score was performed. MNA score was compared between MCI, mild and moderate AD group using one‐way Anova, and the correlation between the degree of cognitive impairment and MNA score was performed. Results Mean age of all patients was 74 years (10 years SD), mean MNA score was 24.6 (SD 3.2). The results showed that patients do not consume enough of the recommended nutrients, especially proteins, fruits and vegetables, daily. Measurements of the median circumference of the forearm and calf revealed that more than (60%) patients had decreased muscle mass, although the Body Mass Index was in the normal range in more than 90% of patients. Six patients had moderate, 34 had mild AD, and 38 had MCI. Only one patient was malnourished, while 23 (29.5%) were at risk of malnutrition. All patient with MCI had normal MNA score. Patients with moderate AD had significantly lower MNA score than patients with MCI (21.5, SD 4 vs 25.5 SD 3.4). No differences were found between other groups. A significant correlation was found between cognitive impairment and MNA (r=0.31, p<0.001) Conclusion Our results suggest that patients with AD need nutritional assessment, especially in the advanced phase. It would be worthwhile to make a nutritional assessment at the first and every subsequent visit of the patient to the outpatient clinic to monitor his or her nutritional status.