Until recently, there is considerable mess regarding the nature of anxiety in dementia. However, anxiety is common in this population affecting from 8% to 71% of prevalence, and resulted in poor outcome and quality of life, even after controlling for depression. Because a presentation of anxiety in the context of dementia can be different from typical early-onset anxiety disorder, it is not easy one to identify and quantify anxiety reliably. Moreover, differentiating anxiety from the depression and/or dementia itself also can be formidable task. Anxiety gradually decreases at the severe stages of dementia and this symptom may be more common in vascular dementia than in Alzheimer's disease. Due to the lack of large randomized clinical trials, optimal treatment and the true degree of efficacy of treatment is not clear yet in this population. However, these treatments can reduce adverse impact of anxiety on patients and caregivers. This article provides a brief review for the diagnosis, evaluation and treatment of anxiety in dementia.