An end mill for milling composite materials, having a defined rotational direction, a shaft and a cutting part, wherein the cutting part extends from a shaft-side end to a front-side end and comprises, in a front length region adjacent to the front-side end of the cutting part, a plurality of first cutting bars with first circumference cutters extending at a positive angle of twist, which are each adjacent to a first groove extending at a positive angle of twist (α1), and comprises, in a rear length region adjacent to the shaft-side end of the cutting part, a plurality of second cutting bars extending at a negative angle of twist (α2) with second circumference cutters, which are each adjacent to a second groove extending at a negative angle of twist (α2), wherein each first cutting bar has at least one third circumference cutter downstream of the first circumference cutter and adjacent to a third groove which has a smaller groove cross-section than the first groove, and each second cutting bar has at least one fourth circumference cutter downstream of the second circumference cutter and adjacent to a fourth groove which has a smaller groove cross-section than the second groove, characterized in that the first cutting bars comprise chip divider grooves which divide at least a part of the first circumference cutters and third circumference cutters into cutter segments, and the second cutting bars comprise chip divider grooves which divide at least a part of the second circumference cutters and fourth circumference cutters into cutter segments, wherein every second first groove extends into the rear length region as far as the shaft-side end of the cutting part when viewed in the circumferential direction of the end mill and divides the second and fourth circumference cutters (1321, 1323) into cutter segments, and every second second groove extends into the front length region as far as the front-side end of the cutting part when viewed in the circumferential direction of the end mill and divides the first and third circumference cutters (1221, 1223) into cutter segments. each first cutting bar has at least one third circumference cutter downstream of the first circumference cutter and adjacent to a third groove which has a smaller groove cross-section than the first groove, and each second cutting bar has at least one fourth circumference cutter downstream of the second circumference cutter and adjacent to a fourth groove which has a smaller groove cross-section than the second groove, characterized in that the first cutting bars comprise chip divider grooves which divide at least a part of the first circumference cutters and third circumference cutters into cutter segments, and the second cutting bars comprise chip divider grooves which divide at least a part of the second circumference cutters and fourth circumference cutters into cutter segments, wherein every second first groove extends into the rear length region as far as the shaft-side end of the cutting part when viewed in the circumferential direction of the end mill and divides the second and fourth circumference cutters (1321, 1323) into cutter segments, and every second second groove extends into the front length region as far as the front-side end of the cutting part when viewed in the circumferential direction of the end mill and divides the first and third circumference cutters (1221, 1223) into cutter segments.