This article is a literature summary and annotated bibliography of research on recruitment for controlled clinical trials published through 1995. It extends and revises a similar review published in this journal a decade ago. The current commentary focuses on intervening developments in recruitment, including diverse populations, HIV trials, primary prevention trials, recruitment strategies, overall planning and management, patient and physician attitudes, adherence, generalizability, and cost. Profound barriers may exist in the recruitment of diverse populations, involving language, cultural factors, beliefs about medical research, and the appropriateness of available protocols. Extensive literature exists on patient and physician barriers to participation. Trials in HIV-infected or AIDs-diagnosed individuals introduce special considerations, including issues of confidentiality, parallel track design, and populations difficult to define and track. Recruitment strategies such as patient registries, occupational screening, direct mail, and the media are now prominent in the literature. Successful planning and management of an overall recruitment plan include piloting strategies, monitoring recruitment by data tracking systems, and hiring quality staff. Generalizability of study results is influenced by the characteristics of participants and by their adherence to study protocol. With increasingly limited funding to conduct clinical trials, efforts to quantify and reduce recruitment costs are being made. While over 4000 titles were identified, primarily by MEDLINE literature search, the articles summarized emphasize data-supported and -confirmed conclusions, and broad coverage of disease areas. We annotate here 91 outstanding articles useful for formulation of overall recruitment approaches in clinical trials.