Publication in the biomedical literature is important because it is the major pathway by which new concepts and discoveries are disseminated amongst scientists. In the last 30 years there has been a dramatic increase, not only in the volume of publications but in the number of authors per article as well. This paper summarizes the current literature on authorship and its proliferation in medicine. From the literature it becomes clear that for biomedical articles, the mean number of authors increased from 1.7 in 1960 to 3.1 in 1990, and there are indications that this trend is even greater in clinical medicine such that single authorship almost has disappeared. Formal guidelines of who should be considered an author have been set by the International Committee of Medical Journal Editors. There are studies suggesting that not all authors on multiauthor papers fulfill these criteria. Inappropriate multiple authorship leads to dilution of authorship responsibility and unjustified citation in curriculum vitae. Recommendations regarding the prevention of inappropriate authorship are given in this paper.