A building stock consisting of 130 medium-rise reinforced concrete buildings were damaged moderately during the recent earthquakes in Turkey. These buildings were rehabilitated by using simple, cost-effective methods where the newly added shear walls comprised the primary lateral load resisting system. In the presented study, different seismic performance evaluation procedures are tested first on the samples of damaged buildings for predicting their observed performances. Then the expected performances of the rehabilitated buildings are evaluated by employing these procedures. It has been found that the nonlinear static procedure is equally successful as the nonlinear dynamic procedure in predicting the observed performances of damaged buildings. The demand-to-capacity ratios obtained from linear spectral procedure are also good indicators of member performances predicted by the nonlinear static procedure. The predicted performance of the rehabilitated buildings evaluated under design excitations revealed that the simple rehabilitation methodology applied systematically should provide life safety under a 475 year seismic hazard. Hence, implementation of the cost effective rehabilitation method presented herein can be suggested as a realistic solution for the vulnerable medium rise concrete buildings in seismic regions.