The RDML file format is developed by the RDML consortium (http://www.rdml.org) and can be used free of charge. The RDML file format was created to encourage the exchange, publication, revision and re-analysis of raw qPCR data. The core of an RDML file is an experiment, not a PCR run. Therefore all the information is collected which is required to understand an experiment. The structure of the file format was inspired by a database structure. In the file are several master elements, which are then referred to in other parts of the file. This structure allows to reduce the amount of redundant information and encourages the user to provide useful information. The Real-time PCR Data Markup Language (RDML) is a structured and universal data standard for exchanging quantitative PCR (qPCR) data. The data standard should contain sufficient information to understand the experimental setup, re-analyse the data and interpret the results. The data standard is a compressed text file in Extensible Markup Language (XML) and enables transparent exchange of annotated qPCR data between instrument software and third-party data analysis packages, between colleagues and collaborators, and between authors, peer reviewers, journals and readers. To support the public acceptance of this standard, both an on-line RDML file generator is available for end users, as well as RDML software libraries to be used by software developers, enabling import and export of RDML data files.