The shortage of water resources in our country has become a major challenge in recent years and evapotrairation (ET) is major water losse in agriculture land use. So, sustainable and optimum water resources management and plant water requirement require the accurate estimation of ET. Estimation of ET from remote sensing data is more appropriate than field methods, because spatial and temporal coverage of this method is very extend and time and cost are optimized. Studies have shown that the surface energy balance algorithm (Sebal) is one of the most appropriate methods in of (ET) estimation. This algorithm used the surface temperature, albedo, vegetation indices and their inter-relationship for calculating surface flux in different types of ground cover. Therefore, the aim of this study was to estimate actual ET with above algorithm in Damaneh region of Isfahan province using Landsat TM 6/1/2009 data. For accurate estimation of ET, the TM image was corrected for geometric and radiometric errors. Surface temperature is a key element in Sebal algorithm. Thus, two well known methods were used to map surface temperature in the study area. I the first method, the sensor temperature converted to actual land surface temperature (LST) by calculating the spectral radiance of band 6 and from NDVI index, and then using of Planck’s law mapping LST was achieved. Results showed that bare ground had maximum temperature and dense vegetation cover had minimum temperature(328° and 291°k respectively). The second method in addition to above parameters in calculation of surface temperature other parameters such a atmospheric water vapor content was also considered. atmospheric water vapor was extracted from band 2, 17, 18 and 19 of MODIS image that was acquired at the same time with TM image, using band ratio technique. In this method also, the minimum and maximum temperature were obtained in crop land and bare soils pixels with 291.8 and 330 ° K , respectively. The both methods results were compared with observation data. according to the results, the first method had higher accuracy than second method. To estimate ET using Sebal algorithm, all input parameters of Sebal including surface temperature(obtained from first method), surface albedo, vegetation indices, surface emissivity,, incoming and outgoing short and long radiation, soil heat flux, sensible heat flux, evaporative fraction were calculated using available equations and then daily ET was calculated in millimeters per day. According to extracted ET map of the study area, ET rates range from 0.0002 to 7.203 ET mm/day. Finally to assess the accuracy of mapping ET, Potential evapotrairation of the region was calculated using FAO - Penman – Manthis technique and its actual evapotrairation map was produced crop coefficient resulting from NDVI that extracted from TM image reflective bands. Results showed that there was a high relationship between ET resulted from Sebal and the FAO - Penman – Manthis techniques (r 2 =0.97,P 01). In general, it can be said that the estimation of ET in broad agricultural lands from remote sensing data i more applicable and can be used as a useful tool for determining plant water requirements and management of water resources. Key words : ET, TM, MODIS, LST, SEBAL , FAO - Penman–Manthis.