The performance of a small modified European grain combine harvester CICORIA, in harvesting sunflower Crop was investigated. Effects of some important parameters such as combine forward speed, seed moisture content, harvesting direction, rotor speed, and rotor-concave clearance on the combine performance were studied. Results showed that the optimum condition obtained at forward speed of 3.3 km/h, seed moisture content of 15.15% (db) Results also indicated that total seed loss of 40.02 kg/fed, energy requirements of (11.38 kW.h/ton), seed production of 1739 kg/h, fuel consumption of 5.5 L/h and total combine processing efficiency of 97.27% were obtained .