A rotor blade for a wind power installation, which extends in a longitudinal direction with a profile course from a blade connector to a blade tip, wherein the profile course contains at least one profile (200, 300), comprising: - a suction side (201, 301) and a pressure side (202, 302), - a relative profile thickness of greater than 25%, - a profile chord (203, 303), which extends between a leading edge (204, 304) and a trailing edge (205, 305) of the profile (200, 300) and has a length which defines the profile depth, - a mean line (230, 240, 250, 330) which extends at least partially below the profile chord (203, 303), thus in a position in a region between the profile chord (203, 303) and the pressure side (202, 302), - a convex region (206, 306) which extends on the suction side (201, 301) from the trailing edge (205, 305), and - a convex region (207, 307) which extends on the pressure side (202, 302) from the trailing edge (205, 305), wherein the convex region (207, 307) on the pressure side (202, 302) defines a rounded transition region of the pressure side (202, 302) to the trailing edge (205, 305), characterized in that the mean line (230, 240, 250, 330) has, in the region in which the mean line (230, 240, 250, 330) is defined by the convex region (207, 307) extending on the pressure side (202, 302) from the trailing edge (205, 305) and the convex region (206, 306) extending on the suction side (201, 301) from the trailing edge (205, 305), a rear local minimum (231, 241), which is situated below the profile chord (203, 303), thus in a position in a region between the profile chord (203, 303) and the pressure side (202, 302), and in that the mean line (230, 240, 250) has, in a region in which the mean line (230, 240, 250) is defined by a convex region extending on the pressure side from the leading edge and the convex region extending on the suction side (201, 301) from the leading edge (204, 304), a front local minimum (232, 242, 251), which is situated below the profile chord (203, 303), thus in a position in a region between the profile chord (203, 303) and the pressure side (202, 302), and/or in that the entire mean line (230, 240, 250, 330) extends below the profile chord (203, 303), thus in a position in a region between the profile chord (203, 303) and the pressure side (202, 302). - a suction side (201, 301) and a pressure side (202, 302), - a relative profile thickness of greater than 25%, - a profile chord (203, 303), which extends between a leading edge (204, 304) and a trailing edge (205, 305) of the profile (200, 300) and has a length which defines the profile depth, - a mean line (230, 240, 250, 330) which extends at least partially below the profile chord (203, 303), thus in a position in a region between the profile chord (203, 303) and the pressure side (202, 302), - a convex region (206, 306) which extends on the suction side (201, 301) from the trailing edge (205, 305), and - a convex region (207, 307) which extends on the pressure side (202, 302) from the trailing edge (205, 305), wherein the convex region (207, 307) on the pressure side (202, 302) defines a rounded transition region of the pressure side (202, 302) to the trailing edge (205, 305), characterized in that the mean line (230, 240, 250, 330) has, in the region in which the mean line (230, 240, 250, 330) is defined by the convex region (207, 307) extending on the pressure side (202, 302) from the trailing edge (205, 305) and the convex region (206, 306) extending on the suction side (201, 301) from the trailing edge (205, 305), a rear local minimum (231, 241), which is situated below the profile chord (203, 303), thus in a position in a region between the profile chord (203, 303) and the pressure side (202, 302), and in that the mean line (230, 240, 250) has, in a region in which the mean line (230, 240, 250) is defined by a convex region extending on the pressure side from the leading edge and the convex region extending on the suction side (201, 301) from the leading edge (204, 304), a front local minimum (232, 242, 251), which is situated below the profile chord (203, 303), thus in a position in a region between the profile chord (203, 303) and the pressure side (202, 302), and/or in that the entire mean line (230, 240, 250, 330) extends below the profile chord (203, 303), thus in a position in a region between the profile chord (203, 303) and the pressure side (202, 302).