A quasi-biennial oscillation with features characteristic of equatorial coupled modes is found in the equatorial Atlantic Ocean. The origins of the phenomenon are investigated by using a coupled atmosphere-ocean general circulation model, in which the fully coupled domain is restricted to the Tropical Atlantic (20 ¿S--30 ¿N). The simulations capture a similar oscillation regardless of whether sea surface temperatures prescribed outside the coupled domain correspond to the observed or the climatology (i.e., lack year-to-year variability). It is concluded that the equatorial Atlantic hosts a quasi-biennial oscillation generated by coupled atmosphere-ocean interactions internal to the basin with little influence from remote events, even from El Ni¿o/Southern Oscillation. ¿ 2001 American Geophysical Union