During the past few decades the critical earthquake model, which is based on observations concerning accelerating seismic deformation and concepts of the critical point dynamics, has been proposed by various seismologists as a useful tool for intermediate-term earthquake prediction. A refined approach of this model has been previously applied to search for preshock (critical) regions in the southern Aegean, using all available data until the middle of 2002. A critical region corresponding to a large mainshock had been identified (Papazachos et al., 2002a,b) in the southwestern part of the Aegean, near the Cythera island. The predicted (in 2002) parameters for this ensuing earthquake are φ = 36.5° N, λ = 22.7° E for the epicental geographic coordinates (with a model uncertainty of 120 km), focal depth ≤100 km, moment magnitude M 6.9 ± 0.5, and origin time tc = 2006.4 ± 2.0. The generation of the strong Cythera earthquake on 8 January 2006 with M 6.9, epicenter coordinates φ = 36.2° N and λ = 23.4° E and a focal depth of h = 65 km satisfies this intermediate-term prediction. The region where significant macroseismic effects were anticipated from the predicted mainshock (Cythera, south Peloponnesus, west Crete, and west Cyclades) corresponds to the area where damage by the 8 January 2006 strong earthquake has been observed. The verification of this prediction is strong evidence that the intermediate-term prediction of strong earthquakes is potentially feasible, but additional forward testing of the model is needed to validate this result.