With the increase of sensitive loads in industrial and commercial customers, more attention has been paid to the power quality problems. Voltage sag is among the major power quality problems that cause interruptions in production lines that result in significant losses. Power quality mitigation devices, that provide different protection levels, can be adopted to match individual customer¡¦s special needs. This thesis presents a cost-benefit assessment of various voltage sag mitigation options at locations with different types of distribution feeders and customers. Simulation results have revealed that using the assumed power quality cost data, the installation of small capacity and low cost UPS has the highest benefit/cost ratio in all the options tested.