In Japan the prevalence of dementia has increased considerably, and pharmacists are involved in addressing these patients' medication-related problems. Here, we determined whether pharmacists' comprehensive assessment of medication proˆles could reduce the burden of dementia patients' medication-related problems. In this historical cohort study 120 community pharmacies were randomly selected, and participating pharmacists completed questionnaires concerning comprehensive assessment of patient medication proˆles, using a``start'' questionnaire for patients prescribed medication prior to or during the study period and a``follow-up'' questionnaire for patients who subsequently visited pharmacies for prescriptions. Numbers and details of problems and solutions implemented by pharmacists and identiˆed in the start and follow-up questionnaires were compared. Changes in start and follow-up scores were also compared between patients whose problems were identiˆed by pharmacists (identiˆed group) and those whose problems were not (nonidentiˆed group). Data were collected for 349 patients issued medication by 60 pharmacies. The most common medication-related problems identiˆed in the start survey were key person's understanding of donepezil (60 cases) and other dementia treatments (60 cases), and adherence to treatment (53 cases). Solutions implemented by pharmacists included gathering information regarding drug administration and dementia awareness from the key person and providing pharmaceutical counseling and instruction. Subsequently, problems related to understanding of dementia treatment, understanding donepezil, and adherence were resolved by 70.0%, 65.0%, and 58.5%, respectively. Pharmacists' comprehensive assessment of medication proˆles could eŠectively solve dementia patients' medication-related problems.