BACKGROUND: For an early detection and prevention of dementia, there are growing concerns about the high-risk group for dementia and mild cognitive impairment. With an increase of obesity and its complications, obesity has become a major public health problem. Therefore, the aim of this study was to investigate the relationship between obesity and the high probability of dementia. METHODS: This study was done with subjects aged 60 to 89 years who visited a health promotion center, from April 1, 2008 to April 30, 2008. A total of 293 subjects (164 males and 129 females) were included in the evaluation of cognitive function using the Korean version of the Seven Minutes Screen test. Logistic regression models were used to analyze the association between obesity and the high-risk group for dementia. RESULTS: Among a total of 293 subjects, 71 subjects (29 males and 42 females) had a high probability of dementia. When compared to normal body mass index (BMI) group, overweight and obesity groups had about a 2.2-fold and 2.4-fold higher probability of dementia (95% confidence interval [CI], 0.97 to 4.99 and 95% CI, 1.07 to 5.46, respectively). When compared to non-obese and non-abdominal obesity group, non-obese and abdominal obesity group and obese and abdominal obesity group had about a 1.5-fold and 2.0-fold higher probability of dementia (95% CI, 0.59 to 3.95 and 95% CI, 1.09 to 3.84, respectively). CONCLUSION: This study shows that as the BMI increased, subjects had a higher probability of dementia; additionally, it suggests that abdominal obesity could be related to a higher probability of dementia.