The accurate simulation of the equatorial sea surface temperature (SST) variability is crucial for a proper representation or prediction of the El Ni?o-Southern Oscillation (ENSO). This paper describes the tropical variability simulated by the Max Planck Institute (MPI) for meteorology coupled atmosphere-ocean general circulation model (CGCM). A control simulation with pre-industrial greenhouse gases is analyzed, and the simulation of key oceanic features, such as SST, is compared with observations. Results from the 400-yr control simulation show that the model’s ENSO variability is quite realistic in terms of structure, strength, and period. Also, two related features (the annual cycle of SST and the-phase locking of ENSO events), which are significant in determining the model’s performance of realistic ENSO prediction, are further validated to be well reproduced by the MPI climate model, which is an atmospheric model ECHAM5 (which fuses the EC for European Center and HAM for Hamburg) coupled to an MPI ocean model (MPI-OM), ECHAM5/MPI-OM.