In order to evaluate the impacts of land use change, the quantification of landscape structure through relevant metrics can be used. These metrics are appropriate owing to the fact that they are measured easily and take low cost and time. The goal of the present study is to investigate the ecological impacts of land use change on the natural structure of the Gharesoo Watershed in order to identify the highly affected areas. Firstly, the amount of land use change between 1984 and 2013 was calculated. Then, landscape metrics were used to investigate the spatial patterns of land use change. Finally, an ecological impact index based on current land use was established. The results showed that during the period studied, areas of forest and agriculture have decreased by 12 and 5 percent respectively, and other uses including residential-industrial, rangeland, and transportations have increased by 292, 143, and 176 percent respectively. Landscape metrics analysis indicated a decrease in compactness and an increase in fragmentation and degradation of the landscape. According to the ecological impact index map, approximately 28 percent of the region is exposed to high and very high impacts. These areas can be used as a base for future studies and may be earmarked for intervention measures such as improving land management and decreasing fragmentation.