The aim of this study was to determine of the mechanical losses that occurred during threshing and after threshing the processing from the paddy to rice depend on threshed at different cylinder speeds by the combine harvester. Another purpose is to determine the effect of the cylinder rotational speed on grain losses and broken germination. According to results, the effect of cylinder rotational speed of combine harvester has been found significant on the amount of broken grain and germination rate (p<0.01). The broken grain has increased with increase of cylinder rotational speed, the germination rate decreased. While the lowest broken grain rate was 0.912% at 650 rpm, the highest broken grain was obtained at 1050 rpm as 4.100%. However, there has been a gradual decrease in germination rates. While the rate of germination rate at 650 rpm was 95.4%, this ration dropped to 85% at 950 rpm and 78% at 1050 rpm. The cylinder rotational speed selected for threshing significantly affected the head rice yield parameters. The lowest broken grain rate was obtained as 6.876% at 650 rpm, while the highest rate was obtained at 950 rpm as 9.072%. The other side, the highest unbroken rate was achieved as 62.955% at 650 rpm, this rate decreased due to the increase in the number of revolutions. The lowest unbroken ratio of grain was obtained at 1050 rpm as 9.168%. The bran ratio increased from 0.846 percent to 1.774%. The lowest brain rate was achieved as 0.846% at 650 rpm, while the highest rate was achieved at 1.774% at 1050 rpm. Head rice yield decreased slightly as the cylinder speed increased. While this rate was 70.67% at 650 rpm, it was 68.87% at 1050 rpm. A similar situation has been achieved in the amount of husk. While the rate of grains at 650 rpm, which is the lowest, is 29.324%, this ratio has increased slightly. Husk ratio, on the other hand, were changed between 29.32% and 31.30%.