Peer reviewed biomedical journals are expected to publish accurate and important information. In the process, numerous ethical issues may arise from within both the editorial and the research communities. This article focuses on four general ethical issues: authorship, peer review, duplicate or repetitive publication, and conflict of interest. Issues of authorship include multiple authorship, misconduct among co-authors, guest and honorary authorship, order of authorship, and credit for those not qualifying for authorship. Peer review attempts to ensure that what is published is valid. Ethical issues in peer review include confidentiality of the manuscript, potential editor and reviewer bias, and conflict of interest on the part of the reviewer. Duplicate or repetitive publication, in which the same information is reported two or more times, can damage a journal's reputation for publishing new and important information and can waste its re-sources. Conflicts of interest, in which financial and personal considerations may affect the investigator's personal judgment, can seriously damage the integrity of the author and of the journal. Increased awareness of these ethical issues should stimulate all those involved in the field to take an active role in promulgating and enforcing the highest ethical standards in biomedical publications.