The Marine Productivity (MarProd) programme data set comprises physical, biological and biogeochemical data, including hydrographic profiles (temperature, salinity, fluorescence, dissolved oxygen, photosynthetically active radiation (PAR)), and samples of nutrients, suspended particulate material, dissolved material, phytoplankton and zooplankton. These data were supplemented by continuous underway measurements of bathymetry, surface hydrography (temperature, salinity, fluorescence and attenuance), meteorology (wind speed and direction, PAR and total incident irradiance, air temperature, humidity and atmospheric pressure), remote sensing of sea surface temperature and ocean colour, and by production experiments. The data were collected in UK shelf seas and the North Atlantic Ocean between 2000 and 2002. Surface biogeochemical parameters (nutrients, photosynthesis, production, suspended particulate material and dissolved organic material) were measured during cruises in the Irish Sea in May, June and July 2001, while ongoing hydrographic and plankton time-series at Plymouth Marine Laboratory's L4 sampling station are also included in the data set. However, the bulk of the data were collected during a major fieldwork campaign of four dedicated research cruises on RRS Discovery between November 2001 and December 2002. A total of over 800 gear deployments were performed at 159 stations mainly distributed in the Irminger Sea and Iceland Basin, facilitating the measurement of water mass distribution, velocity field and mixed layer properties. A comprehensive water sampling programme was undertaken for the purposes of plant pigment and microscopic analyses; biomass estimations of different taxonomic/functional groups of microplankton (picoplankton, phytoplankton and microzooplankton); high resolution profiles of inorganic nutrient concentrations; and determination of abundance of key zooplankton species (Calanus finmarchicus, Oithona spp. and euphausiids). Process studies were undertaken to obtain information about factors controlling the reproduction, growth, mortality and behaviour of individual species using physiological studies (feeding experiments, egg production and nauplii development, species interactions) and analyses of biochemical composition (lipids and hormones studies, analyses of carbon/nitrogen and stable isotope ratios composition). Phytoplankton primary production was measured using carbon uptake on the last two cruises and additional data were collected using a Fast Repetition Rate Fluorometer (FRRF) through continuous surface underway sampling and vertical deployments. MarProd's main objective was to investigate the population dynamics of key zooplankton species in UK shelf seas and in the northern Atlantic with emphasis on the manner in which physical factors such as water temperature and oceanic currents influence their distribution, abundance and productivity. The MarProd Programme involved researchers from numerous institutions from the UK, Ireland and Spain. The data are archived at the British Oceanographic Data Centre.