Monthly tropical Atlantic sea level is computed from Geosat altimetry for 1 year beginning in November 1986. The analysis is carried out using a collinear technique on 1¿¿1/3¿ grid. Monthly maps are presented, and the seasonal changes in the major currents are analyzed in the context of previous results from in situ data. Between 10¿ and 20¿N the sea level shows a westward North Equatorial Current from July to April with the most persistent westward currents in the western part of the basin. Between 4¿ and 6¿N an intense North Equatorial Countercurrent (NECC) exists throughout much of the year with geostrophic velocities exceeding 1 m/s. The NECC is intense in October--November, but decays rapidly between December and January. In May the NECC returns, and intensifies uniformly in later months. The branch of the South Equatorial Current south of the equator prevails throughout most of the year west of 10¿W. The strongest pressure gradient occurs between March and July. The zonal sea level slope along the equator reflects intensification of currents and large-scale redistribution of water in response to seasonal winds. The seasonal change in zonal slope obtained here is similar to that estimated from in situ observations, but the changes are larger by 30%. Of the month-to-month variability of sea level, over half is described by the annual cycle. The strongest annual variability is in the countercurrent region, where the phase of the seasonal signal changes rapidly, along northwest Africa and the Gulf of Guinea. The latter two appear to be related to seasonal upwelling. ¿ American Geophysical Union 1989