PURPOSE: To analyse the type of enquiries to a drug information service in Germany, available exclusively for patients. METHODS: Sociodemographic characteristics of the patients who used the service, number and kind of drugs taken, existing diseases, reasons for enquiry as well as type of answers provided were recorded. For the present evaluation we analysed all enquiries to the service from August 2001 to January 2007. RESULTS: A total of 5587 enquiries were received. 5013 enquiries from 4091 patients were available for further analysis in detail. The patient group using the service most frequently were women between 61 and 70 years (23.3%). 1457 enquiries (29.1%) were made by patients who had contacted the information service once or several times before. The group of drugs most often asked about were cardiovascular drugs (33.4%), followed by drugs for the nervous system (16.2%) and for the alimentary tract and metabolism (12.4%). On average, each patient had questions about 2.6 (median 1; 1-22) drugs simultaneously. Common reasons for contacting the service were adverse drug reactions (22.1%), the need for general information about the drug (19.9%), information about therapy (12.4%) and drug interactions (10.2%). CONCLUSIONS: A lot of patients need additional information about their medication, especially concerning drug groups that are frequently prescribed. The presented drug information service can be one helpful tool to counteract these information deficits and to increase patients' knowledge about their drugs.