To describe the prevalence of opioid use in persons with a cognitive impairment compared with cognitively intact persons and to explore factors associated with opioid prescription. A search was made in PubMed (Medline), Embase, Cochrane, Central, Cinahl, PsychInfo and Web of Science and additional articles were identified by manual search of reference lists. Titles and abstracts were screened and eligible articles reviewed in full-text. A citation check was performed on the included articles for a complete search. Risk of bias of the included studies was assessed using an appropriate tool. The search yielded 610 unique hits and an additional 33 records were identified via reference checking. After screening, 23 studies were included. A citation tracking was performed for these 23 articles using Web of Science, which yielded an additional 421 articles for a second screening. After the second screening, 24 studies were included. Opioid use was divided into three classes: weak, strong, and weak and strong combined. In several articles there were more than one study conclusion on different opioid classes or in a different setting. Analysis was performed on the prevalence of opioid use (prescription rates) and the dosage of opioids. The 24 studies yielded a total of 35 study conclusions related to prescription rates and dosage. Of these, four showed a higher use of opioids in persons with a cognitive impairment, 14 an equal distribution, and 17 showed lower opioid use in cognitively impaired persons. This systematic review provides evidence for general undertreatment of pain with opioids in persons with a cognitive impairment.