Background: Suboptimal prescribing, including the prescription of potentially inappropriate medications (PIM), is frequent in patients aged 65 years and older. PIMs are associated with adverse drug events, which may lead to hospital admissions and readmissions for the most serious cases. Several tools, known as lists of PIMs, can detect suboptimal prescription. Objective: This systematic review aimed to identify which lists of PIMs are associated with hospital readmission of older patients. Patients and methods: MEDLINE, the Cochrane Library, EMBASE, and clinicaltrials.gov were searched for the period from 1 January 1991 up to 12 May 2022 to identify original studies assessing the association between PIMs and hospital readmissions or emergency department (ED) revisits within 30 days of discharge in older patients. This study is reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 Checklist, and the risk of bias was assessed with the Newcastle-Ottawa Quality Assessment Scale for Cohort Studies (NOS) and the revised Cochrane risk-of-bias tool for randomized trials (RoB 2). Results: A total of six studies presenting four different lists of PIMs were included. Readmission rates varied from 4.3 to 25.5% and the odds ratio (OR) between PIMs and hospital readmission varied from 0.92 [95% confidence interval (CI) 0.59; 1.42] to 6.48 [95% CI 3.00; 14.00]. Only two studies found a statistically significant association between a list of PIMs and hospital readmission. These two studies used different tools: the Screening Tool of Older Person's Prescriptions (STOPP) and the Screening Tool to Alert Doctors to Right Treatment (START) and a combination of Beers Criteria® and STOPP and START. Conclusion: This systematic review shows that the association between list of PIMs and 30-day unplanned readmissions remains unclear and seems dependent on the PIM detection tool. Further studies are needed to clarify this association. PROSPERO registration number CRD42021252107.