Most scientific research is conducted properly and reported honestly but a few authors invent or manipulate data to reach fraudulent conclusions. Other types of misconduct include deliberately providing incomplete or improperly processed data, failure to follow ethical procedures, failure to obtain informed consent, breach of patient confidentiality, improper award or denial of authorship, failure to declare competing interests, duplicate submission and plagiarism. Editors, peer reviewers and publishers may also act wrongly. Good practice guidelines are available from the International Committee of Medical Journal Editors (The Vancouver Group) and the Council of Science Editors, amongst others. The Committee on Publication Ethics provides flowcharts to assist editors deal with authorial misconduct. Examples are provided of cases involving epidemiological or public health research, reported to COPE over the last 9 years. Suggestions are offered as to how misconduct might be handled in future.