Clinical pharmacologists have a service role in the provision of drug information to individuals both in hospitals and primary health care. We present here a systematic approach in answering questions in a drug information centre (DIC), and describe the working method and the documentation of the work in a question answer (Q/A) data base. Drugline is a full-text data base offering problem-oriented drug evaluation comparable to a clinical consultation. The drug information is produced in a non-commercial drug information centre sponsored by the national health care sector and the National Corporation of Swedish Pharmacies, and run jointly by clinical pharmacologists and pharmacists. A minor part of Drugline is available in English for online searching, in parallel with Medline at the database host, the Medical Information Centre at the Karolinska Institute Library and Information Centre, and the users represent mainly medical libraries, hospital pharmacies, university clinics, and the pharmaceutical industry. A network of DICs has been organized in Swedish university hospitals with access to Drugline for searching and the storage of questions and answers. This network has the potential for expansion throughout Europe. It offers the unique possibility of complementing drug product information with problem-oriented drug information emerging from cases in the real world of prescribing.