METEOR cruise M45 took place in the North Atlantic Ocean in 1999 and consisted of five legs. The research activities during the METEOR cruise M45/1, which started in Malaga on 19 May 1999, were related to the scientific programs CANIGO/ESTOC and DOMEST. The DOMEST project concentrates on marine technology and data transmission, mainly tested in the Canary Island region. On this cruise the CANIGO/ESTOC project concentrated on seafloor and water probing. In the morning of June 8 the RV METEOR arrived in Lisbon. During the second leg (Lisbon - St. John's) the aim was the investigation of water mass spreading and mixing within the eastern basin of the eastern North Atlantic. The work was part of the yearly field programmes of the "Sonderforschungsbereich" SFB 460. Elements of the repeat hydrographic survey in the Iceland Basin included observations with CTD and rosette sampler. For determining deep circulation and water mass transformation, nutrients and tracer samples (CFCs, tritium/helium) were taken. In addition an array of moored current meters for monitoring the Overflow Water close to the Reykjanes Ridge was recovered. The array was then partly redeployed for an additional year. RAFOS float observations for the determination of the drift of Labrador Sea Water in the eastern basin were continued during M45/2. The third leg (St. John's - St. John's) focused on the deep circulation and water mass distribution of the Labrador and Irminger seas, also within the context of the SFB 460. The distribution of water masses and circulation was studied along standard repeat sections using current profiling, hydrography and tracer (Freon, tritium/helium) observations. In the Labrador Sea, a number of tomography, convection and boundary current moorings were recovered and redeployed for measuring deep convection activity. A new moored array was deployed off the Grand Banks to measure the export of Deep Water out of the Subpolar North Atlantic. The fourth cruise leg (St. John's - Rendsburg) was devoted to mooring work and hydrographic measurements on sections normal to the southeastern slope of Greenland. It was aimed at repeatedly describing the state of the Denmark Strait overflow as one of the contributions to the EU Project VEINS on the Variability of Exchanges in the Northern Seas. Leg M45/4 METEOR ended on 1 September in the ship yard in Rendsburg. Cruise leg M45/5 started on 1 October 1999 in Bremen and ended on 3 November 1999 in Las Palmas. It was subdivided into two parts with an interim stay in Las Palmas during 20 - 22 October. During the first leg (M45/5a), sedimentological investigations and plankton sampling were carried out in the North Sea, Azores Frontal System and off Cape Ghir (NW Africa) with the purpose to collect data on the reconstruction of paleo-environmental conditions of these regions. During the second leg (M45/5b), equipment testing, mooring work and water column measurements were carried out. Water column sampling, including primary production and particle flux measurements, were carried out around the time-series station ESTOC (European Station for Time-series in the ocean, Canary Islands) as well as off Cape Ghir., METEOR-Berichte