The River Macrophytes Database (RMD) is a Microsoft Access database constructed to house data on the plant communities of rivers in Great Britain and Northern Ireland. It includes data from over 7000 survey sites and is the most comprehensive database of its kind. Data have been collected from all over the UK between 1977 and the present day, following the methods of Holmes et al. (1999). The data held in the RMD are the result of collaborative work across all four statutory nature conservation bodies: Scottish Natural Heritage (SNH), Natural England (NE), Natural Resources Wales (NRW, formerly CCW) and the Northern Ireland Environment Agency (NIEA). The River Macrophytes Database can be downloaded from the JNCC website: https://hub.jncc.gov.uk/assets/0a26368d-400c-44e1-beaf-d4b89b7badcd#extent-detail