A database of randomised clinical trials (RCTs) in pain research published from 1950 to 1990 was created following an extensive literature search. By applying a refined MEDLINE search strategy from 1966 to 1990 and by hand-searching more than 1,000,000 pages of a total of 40 biomedical journals published during the period 1950-1990, more than 8000 RCTs were identified. The RCTs were published in more than 800 journals and over 85% appeared between 1976 and 1990. If the trend of the last 15 years persists, a total of more than 15 000 RCTs will be published in pain relief by the year 2000. A detailed description of methods to ensure efficient use of resources during the identification, retrieval and management of the information in pain relief and other fields is given. Emphasis is made on the importance of refining MEDLINE search strategies, on the use of volunteers to hand-search journals and on careful monitoring of each of the steps of the process. The potential uses of the database to guide clinical and research decisions are discussed.