Feasible retrofitting solutions have been developed for selected residential midrise apartment buildings under high seismic risk in Istanbul. A feasible solution is considered as the optimal combination of cost, downtime, disturbance, technical applicability and social impact. The retrofit solutions include various combinations of strength and ductility enhancement at member and system levels. All solutions are classified into two major alternatives of external and internal retrofitting. External retrofitting mainly consists of exterior coupled shear walls attached to the building perimeter whereas the basic elements of internal retrofitting are concrete infilled shear walls. Secondary elements are also employed in both retrofitting solutions where necessary. They are basically the existing masonry partition walls enhanced by applying mesh reinforcement, FRP sheets or thin precast concrete panels on their surfaces. The seismic response from each alternative is calculated by simplified performance assessment procedures, and their acceptability is verified. Then their feasibility is tested against the "demolish and rebuild" alternative through a cost-benefit analysis. All solution alternatives have been reported to the building owners for their review. Exterior retrofitting has prevailed in most buildings as the feasible solution. Copyright © (2006) by Earthquake Engineering Research Institute.