The Journal of Korean Medical Science (JKMS) follows the recommendations for authorship by the International Committee of Medical Journal Editors (ICMJE, 2008, www.icmje.org) and the Good Publication Practice Guidelines by the Korean Association of Medical Journal Editors (KAMJE, 2008, www.kamje.or.kr). The Uniform Requirements by the ICMJE recommends authorship as follows. "Authorship credit should be based on 1) substantial contributions to conception and design, acquisition of data, or analysis and interpretation of data; 2) drafting the article or revising it critically for important intellectual content; and 3) final approval of the version to be published. Authors should meet conditions 1, 2, and 3." Beyond the ICMJE recommendations, the KAMJE guidelines suggest that all authors should make a substantial intellectual contribution to the publication, the guidelines warn against authorship abuse, and list common types of abuse. Authorship is an important aspect of research publication, and all involved authors should agree whole contents of the document including authorship. Contributors should be differentiated from authors as recommended by the ICMJE. JKMS does not allow multiple corresponding authors for one article even when it is reporting on a multicenter study. Only one author should correspond with the editorial office and readers for one article. JKMS accepts notice of equal contribution for the first author when the study was clearly performed by co-first authors. However, the present issue of JKMS (Vol. 25 No. 5: 734-7) publishes one article which has two corresponding authors. The article, which is titled "Optimal Waist Circumference Cutoff Values for Metabolic Syndrome Diagnostic Criteria in a Korean Rural Population", is published exceptionally because the authorship policy of JKMS has not been open declared yet. The authorship policy is declared open through this editorial and also at the homepage of JKMS, http://jkms.org. JKMS does not correct authorship after publication unless any mistake has been made by the editorial or publishing staff. Authorship may be changed before publication but after submission when an authorship correction is requested by all authors involved.