Background Information on medication use and drug-related problems is important in the preparation of clinical medication reviews. Critical information can only be provided by patients themselves, but interviewing patients is time-consuming. Alternatively, patient information could be obtained with a questionnaire. Objective In this study the agreement between patient information on medication use and drug-related problems in older patients obtained with a questionnaire was compared with information obtained during an interview. Setting General practice in The Netherlands. Method A questionnaire was developed to obtain information on actual medication use and drug-related problems. Two patient groups C65 years were selected based on general practitioner electronic medical records in nine practices; I. polypharmacy and II. C1 predefined general geriatric problems. Eligible patients were asked to complete the questionnaire and were interviewed afterwards. Main outcome measure Agreement on information on medication use and drug-related problems collected with the questionnaire and interview was calculated. Results Ninety-seven patients participated. Of all medications used, 87.6 % (95 % CI 84.7-90.5) was reported identically in the questionnaire and interview. Agreement for the complete medication list was found for 45.4 % (95 % CI 35.8-55.3) of the patients. On drug-related problem level, agreement between questionnaire and interview was 75 %. Agreement tended to be lower in vulnerable patients characterized by C4 chronic diseases, C10 medications used and low health literacy. Conclusion Information from a questionnaire showed reasonable agreement compared with interviewing. The patients reported more medications and drug-related problems in the interview than the questionnaire. Taking the limitations into account, a questionnaire seems a suitable tool for medication reviews that may replace an interview for most patients.