Ships are significant emissions sources, especially in port areas. Besides other emission sources, they have remarkable air pollution impacts on residential areas near ports. It is well known that these emissions have deleterious impacts on both human health, and ecosystems. The biggest ports are generally located near highly populated cities. Therefore, emissions occurred due to shipping activities in ports have a significant importance. This study examines shipping emissions at berth by using data of ships calling in Iskenderun Port in 2013 and compares the environmental performance of using shore side electricity. The study also investigates the external costs associated with the impacts of emissions on climate change, air quality, and human health. According to the results, utilization of shore side electricity instead of auxiliary engines in ports provide significant benefits on environmental and economic issues. In case of Iskenderun Port, it is concluded that shore side electricity eliminates approximately $ 23 million of external costs per year.