The December 2004 Sumatra earthquake triggered a massively destructive tsunami that affected several coastal areas in the Indian Ocean. In this study, very high resolution IKONOS satellite images acquired before and after the tsunami were used to study the changes of the coastal morphology in the Northwestern coast of Sumatra. The coasts were eroded during the tsunami. At some stretches of the coast, the coastline receded by as much as 500 m. About 13 months after the tsunami, new beaches were formed at many areas along the coastline. The widths of the newly formed beaches exceeded those of the pre-tsunami coast. In areas where anthropogenic modifications have occurred before the tsunami, the coastline remained eroded after 13 months and no evidence of recovery was observed.