As population ageing means that dementia is becoming more prevalent, it is increasingly important that clinicians from all types of practice are familiar with assessing patients who have possible cognitive impairment. The diagnosis of the syndrome of dementia remains a clinical process, supplemented by relevant investigations including cognitive testing. This paper reviews some of the more commonly used tools for assessing cognition, behaviour and overall functioning in patients with possible or established dementia. Several categories of instruments are considered, including brief screening tests, neuropsychological test batteries, scales for behavioural and psychiatric symptoms, and functional and global assessments. It is recommended that clinicians familiarise themselves with a small number of scales that can be readily employed in everyday practice.