Purpose: medication problems are thought to cause between 10 and 30% of all hospital admissions in older people. This systematic review aimed to evaluate the effectiveness of interventions led by hospital or community pharmacists in reducing unplanned hospital admissions for older people. Methods: eighteen databases were searched with a customised search strategy. Relevant websites and reference lists of included trials were checked. Randomised controlled trials were included that evaluated pharmacist-led interventions compared with usual care, with unplanned admissions or readmissions as an outcome. Two authors independently extracted data and assessed methodological quality. Results: twenty-seven randomised controlled trials (RCTs) were identified; seven trials were excluded. The 20 included trials comprised 16 for older people and 4 for older people with heart failure. Interventions led by hospital pharmacists (seven trials) or community pharmacists (nine trials) did not reduce unplanned admissions in the older population (risk ratios 0.97 95% CI: 0.88, 1.07; 1.07 95% CI: 0.96, 1.20). Three trials in older people with heart failure showed that interventions delivered by a hospital pharmacist reduced the relative risk of admissions. However, these trials were heterogeneous in intensity and duration of follow-up. One trial had a high risk of bias. Conclusions: evidence from three randomised controlled trials suggests that interventions led by hospital pharmacists reduce unplanned hospital admissions in older patients with heart failure, although these trials were heterogeneous. Data from 16 trials do not support the concept that interventions led by hospital or community pharmacists for the general older population reduces unplanned admissions.