Assessing the structure and functionality of rangeland is required to detect early changes in the ecosystem and assist managers to evaluate the effects of their management practices. The both field methods and remote sensing indices can be used to assess rangeland functionality. Rangeland ecosystems are formed by many vegetation patches with different ability to conserve vital resources such as water and nutrients. Landscape Function Analysis (LFA) is a relatively new method to assess the functionality of rangeland ecosystems by assessing soil stability, nutrient cycling and infiltration of a particular site derived from 11 soil surface indicators. Assessing rangeland functionality by remote sensing data also decrease the cost of assessment procedures and measurements error and enhance the accuracy of the results. This study aimed to evaluate the functionality of Steppe and Semi-Steppe rangelands in Isfahan province using field and remote sensing approaches. Three sites in Steppe rangelands of Shahreza with very poor condition and also 3, 4 and 7 sites with very poor, poor and moderate condition,respectively, in Semi-Steppe rangeland of Aghcheh were selected. One transect was established directly downslope in each site randomly and a continuous record of all patch/ inter-patches (including their names, lengths and widths) were recorded. Also in all patches, 11 indicators of soil surface characteristics were measured with three replications and their status were scored according to LFA method and then the functionality indices of all sites including soil stability, infiltration and nutrient cycling were measured accordingly. The landscape functions of studied area were also assessed by some remote sensing indices including leakiness index (LI), Weighted Mean Patch Size (WMPS) index, Lacunarity index and proximity index. Landsat 5 (TM sensor) satellite images obtained at 1/6/2009 was used to calculate the indices. Geometric corrections were applied to the images and studied areas in Aghcheh and Shareza were divided into 12 sub basins with size of 6995 hectares and 4 sub basins with size of 16067 hectares, respectively. The remote sensing indices were calculated in all sub basins. According to the analytical analysis, structural characteristics (number of patches, patch length, patch area index, landscape organization index) and functional indices (infiltration, stability and nutrient cycling status) varied significantly (?= 0.05) between rangeland sites with moderate and very poor condition in Semi-Steppe sites. The changes of these structural and functional characteristics were not significant between range sites with moderate and poor, and poor and very poor range condition. The regression analysis revealed that the values of LI index had a negative linear relationship with NDVI values. In other words, LI values decrease with increassing the percentage of vegetation cover. Other calculated remote sensing indices had positive relationships with NDVI values. According to the results, the functionality of the sites to conserve the vital resources such as water and nutrients and the values of WMPS, lacunarity and proximity indices depend on plant cover, plant density and patch distribution (the distances between the patches) of the sites. Overall, using these indices have considerable capability in assessing the functionality of Steppe and Semi-Steppe rangelands, hence these indices can be used in assessment and monitoring of rangeland ecosystems. Keywords : Rangeland functi on, Structure, Landscape Function Analysis, Landsat TM, Leakiness index, Weighted Mean Patch Size, Lacunarity index, Proximity index