The objective of the present investigation is to develop, manufacture and evaluate sunflower thresher at Agricultural Research Station, Sakha, Kafr El-Sheikh Governorate. A comparative sunflower threshing test was carried out using the Bamby 049 BBY thresher, a modified French made and [Misr (CRS)] local threshers. Three types of threshing drums, triangular flat-bar (01), triangular rasp-bar (02) and triangular spike-tooth (03), four drum speeds, four concave clearance ratios (C1 1C2) and three grain moisture contents were tested to estimate total grain losses, grain damage, threshing efficiency, fuel consumption, power requirement and operating cost. Results indicated that the spike-tooth drum (03) and the clearance ratio of 1.8 gave always better results of the performance evaluation for the modified thresher. Results also indicated that, for optimum performance the thresher's drum speed should be about 9.53 m/s and the grain moisture content ranged from 15.4% to 20.9%. The modified thresher gave better results of the total grain losses, grain damage and fuel consumption compared with other threshers. While the Misr (CRS) thresher gave the minimum values of threshing power requirements (9.26 k W.h/Mg) for the optimum drum speed of 9.53 m/s and the optimum moisture content of 20.9% compared with other threshers. The threshing costs per yield unit of the Misr (CRS), modified Bamby 049 BBy threshers and manual method were 10_0,13.04 and 75.0 LE/Mg, respectively.