The invention relates to a multi-speed gearbox having nine forward gears and one reverse gear, comprising four planetary gear sets (P1, P2, P3, P4), eight rotatable shafts (1, 2, 3, 4, 5, 6, 7, 8) and six shift elements (03, 04, 05, 15, 17, 18), wherein the sun gear of the first planetary gear set (P1) is connected to the fifth shaft (5) which can be coupled to the housing (G) by means of a third brake (05) and can be connected to the drive shaft (1) by means of a first clutch (15), which can be connected to the seventh shaft (7) which is connected to the ring gear of the third planetary gear set (P3) and to the planet carrier of the second planetary gear set (P2) through the second clutch (17) and can be connected to the eighth shaft (8) by means of a third clutch (18), said shaft being connected to the planet carrier of the first planetary gear set (P1) and to the sun gear of the second planetary gear set (P2). The sixth shaft (6) is connected to the ring gear of the second planetary gear set (P2) and to the planet carrier of the fourth planetary gear set (P4). The fourth shaft (4) is connected to ring gear of the first planetary gear set (P1) and to the sun gear of the fourth planetary gear set (P4) and can be coupled to the housing (G) by means of a second brake (04). The third shaft (3) is connected to the sun gear of the third planetary gear set (P3) and can be coupled to the housing (G) by means of a first brake (03). The output shaft (2) is connected to the planet carrier of the third planetary gear set (P3) and to the ring gear of the fourth planetary gear set (P4).