Early in 1985, after being questioned about duplicate data in two of his papers, Robert A. Slutsky, M.D., resigned his appointments as a radiology resident (trainee) and nonsalaried associate clinical professor in the Department of Radiology at the University of California, San Diego. During the following year, faculty committees investigated Slutsky's entire bibliography of 137 articles published in seven years; 77 (including reviews) were classified as valid, 48 were judged questionable, and 12 were deemed fraudulent. The majority of these papers were published while Slutsky was a research or clinical trainee in cardiology, nuclear medicine, and then radiology. Our analysis of this case leads us to conclude that research fraud, although probably rare, in view of the size of the research establishment, may evade detection, and that there are scientists prepared to run the appreciable risk of submitting inaccurate statements for publication. Sophisticated dishonesty can escape detection by peer review and replication. The emphasis on competition and the pressure to produce, while intended to advance the discovery of truth, may foster a conflict between personal career goals and the intellectual motivation of scientists to seek the truth. The scientific community needs to address the issues raised by recent reports of fraud. Each institution and granting agency must have procedures for investigating suspected fraud or unethical practices, procedures that protect both the person who reports such practices and the accused person from premature disclosure. As we heighten awareness, we must avoid a "witch hunt." Deterrence of research fraud is clearly needed, but institution of practices that might stifle originality or discourage cooperative research would be counterproductive.