Cognitive syndromes are commonly encountered among cancer patients, with the elderly being at higher risk. This chapter focuses on the cognitive assessment of older cancer patients and reviews the most commonly seen neurocognitive disorders in oncology settings. Delirium is one of the most common neuropsychiatric complications seen in older adults with cancer. The chapter describes assessment, prevention, management, and treatment of delirium. Commonly used delirium screening and assessment tools are Confusion Assessment Method, Delirium Rating Scale-R-98, Memorial Delirium Assessment Scale, and Nursing Delirium Screening Scale. Dementia is a progressive cognitive decline characterized by impairment in cognitive functioning that interferes with one’s ability to perform activities of daily living independently. This chapter discusses screening and assessment of dementia. Cognitive assessment tools such as Montreal Cognitive Assessment, Mini-Mental State Examination, and Mini-Cog should be used to screen older adults for cognitive deficits. It also talks about cancer or cancer therapy-associated cognitive changes.