BACKGROUND: Older adults with dementia who are on polypharmacy are more vulnerable to the use of potentially inappropriate medications (PIM), which can significantly increase the risk of adverse events and drug-related problems (DRPs). OBJECTIVE: This systematic review and meta-analysis were conducted to map the prevalence of PIM use, polypharmacy, and hyper-polypharmacy among older adults with cognitive impairment or dementia attending memory clinics. METHODS: Ovid MEDLINE, Ovid EMBASE, Scopus, Cochrane Library, EBSCOhost CINAHL, and Ovid International Pharmaceutical Abstracts (IPA) were systematically searched from inception to April 22, 2024. Observational studies assessing the PIMs use among older adults with CI or dementia were screened. A random- effects meta-analysis was conducted to pool the prevalence estimates. RESULTS: Of 5,787 identified citations, 11 studies including 4,571 participants from 8 countries were included. Among all the included studies the pooled prevalence of PIM use was 38% (95% confidence interval (CIn): 27- 50%), highlighting a notable range from 20% to 78%. The analysis identified anticholinergics, benzodiazepines, and non-benzodiazepine sedatives as the most common PIMs. Subgroup analysis revealed a higher pooled prevalence of PIM in the USA (39%; 95% CIn: 10- 78, I2 (%) = 98, 3 studies) and Australia (36%, 95% CIn: 12- 70, I2 (%) = 96, 2 Studies). Additionally, pooled prevalence of polypharmacy and hyper-polypharmacy was reported as (60%; 95% CIn: 46- 73, I2 (%) = 95, 3 studies), and (The prevalence of hyper-polypharmacy was 17.6%; 1 study) respectively. CONCLUSIONS: The definition of PIMs significantly impacts study results, often more than geographical variations. The variability in criteria and tools like the Beers or Screening Tool of Older Persons' Prescriptions (STOPP) criteria across studies and regions leads to differing prevalence rates.