Self-plagiarism is a controversial issue in scientific writing and presentation of research data. Unlike plagiarism, self-plagiarism is difficult to interpret as intellectual theft under the justification that one cannot steal from oneself. However, academics are concerned, as self-plagiarized papers mislead readers, do not contribute to science, and bring undeserved credit to authors. As such, it should be considered a form of scientific misconduct. In this paper, we explain different forms of self-plagiarism in scientific writing and then present good editorial policy toward questionable material. The importance of dealing with self-plagiarism is emphasized by the recently published proposal of Text Recycling Guidelines by the Committee on Publication Ethics (COPE).