Geosat radar altimeter data from repeat cycles 1--38 of the Exact Repeat Mission (ERM) over the period November 1986 to August 1988 have been employed to derive the parameters of the semidiurnal ocean tides of the northwest European continental shelf using a modified form of response analysis. Values for M2 and S2 have been found to be compatible with those of previous empirical tidal maps and are estimated to be accurate to approximately 6 cm. This is an accuracy comparable to, or better than, that provided by current numerical models of the sea. The results imply that altimetric models of the major tidal constituents in most coastal areas should be derivable from Geosat and subsequent altimetry to an accuracy, averaged over the whole coastal area, not previously possible from conventional tide gauge measurement programs or from numerical modeling. ¿ American Geophysical Union 1990