This chapter deals with the discussion on abnormal movements. Abnormal involuntary movements (AIMs) are also known as “dyskinesias”. There are several different varieties of dyskinesia which have different clinical appearances, underlying causes and treatments. Tics and stereotypes may also be considered to be related, but some experts call these “involuntary” because there is an element of voluntary control. AIMs are classified into athetosis, dystonia, hemiballismus, tics, and tremor, which are described broadly in this chapter. The AIM scale is used to assess tardive dyskinesias and other AIMs. This can be useful to monitor progress and response to treatment. In evaluating movement disorder, there are three aspects to the examination i.e. positive phenomena, latent phenomena, and negative phenomena.