Since 1990 the Institute of Biogeochemistry and Marine Chemistry (Hamburg University) has investigated the CO2-system in the eastern North Atlantic. These extensive investigations have yielded plenty of information about the regional and seasonal development of the CO2-system in the mixed layer. At the central JGOFS-station (47°N, 20°W) the total dissolved inorganic carbon decreases from 2100 µmol/kg in early April to 2030 µmol/kg in early August. This is due to biogenic processes and is coupled with a consolidation of the mixed layer depth. However, up to now little is known about the North Atlantic CO2-system in wintertime. The main goal of Meteor 27-activities was to fill this void by measuring total alkalinity (TA), TCO2 and salinity. It was suggested that TCO2 and pCO2 reach a winter maximum with values higher than in April 1992. If that assumption is correct, a higher amount of CO2 would have been removed from the mixed layer by the 'biological pump' during spring and summer. In addition to the inorganic carbon studies, a joint working group from the Institut für Ostseeforschung and the Woods Hole Oceanographic Institution continued their studies of the seasonal development of dissolved organic matter concentrations in the whole water column.