During a cruise over the Atlantic from 40 ¿S to 50 ¿N in March--April 1987 the concentrations of dimethylsulfide (DMS) in the ocean and atmospheric were measured as well as the distribution of its precursor, dimethylsulfoniopropionate (DMSP), and of several biological parameters such as chlorophyll, phytoplankton species, and adenosine-5-triphosphate (ATP) in the surface water. The DMS concentration varied in the range 0.2--2 nmol DMS L-1 (surface water) and 0.05--3 nmol DMS m-3 (atmosphere) in the region of the remote tropical and subtropical Atlantic and increased to 2--10 nmol DMS L-1 (surface water) and 1--8 nmol DMS m-3 (atmosphere) north of 40 ¿N and in the English Channel. Based on these results the mean flux of DMS from the Atlantic to the atmosphere is estimated to be 4--4.65 nmol DMS m-2 min-1. A moderate diurnal variation of atmospheric DMS was found with a minimum during daytime. The DMS concentration in seawater correlated well with the concentration of DMSP and showed a similar trend to ATP, chlorophyll, and some phytoplankton species. ¿ American Geophysical Union 1990