A magnetic separation device comprising: a plurality of magnetising portions for providing a high-gradient magnetic field, each magnetizing portion comprising a first and a second magnetic assembly (3ma, 3mb), each comprising: a plurality of magnets (M1, M2) whereby each of the plurality of magnets (M1, M2) has a north pole, a south pole and a magnet axis extending between the north and south poles, and the plurality of magnets (M1, M2) are arranged one above the other in a direction at least substantially perpendicular to the axis of each magnet in such a manner that the north and south poles of adjacent magnets (M1, M2) are arranged alternately and a space is provide between adjacent magnets (M1, M2); and at least one non-magnetic spacing means arranged in the space between adjacent magnets (M1, M2), each magnet (M1, M2) preferably comprising a permanent magnetic material or a ferrous magnetic material, the magnetic separation device further comprising an array of sample vessel retaining portions, wherein the first and the second magnetic assembly (3ma, 3mb) of each magnetizing portion are arranged in parallel relation, on opposing sides of and proximate each sample vessel retaining portion and wherein corresponding magnets in the first and the second assembly (3ma, 3mb) are opposed such that the north pole of a magnet in the first magnetic assembly is arranged opposed to the south pole of a magnet in the second magnetic assembly and vice versa. a plurality of magnetising portions for providing a high-gradient magnetic field, each magnetizing portion comprising a first and a second magnetic assembly (3ma, 3mb), each comprising: a plurality of magnets (M1, M2) whereby each of the plurality of magnets (M1, M2) has a north pole, a south pole and a magnet axis extending between the north and south poles, and the plurality of magnets (M1, M2) are arranged one above the other in a direction at least substantially perpendicular to the axis of each magnet in such a manner that the north and south poles of adjacent magnets (M1, M2) are arranged alternately and a space is provide between adjacent magnets (M1, M2); and at least one non-magnetic spacing means arranged in the space between adjacent magnets (M1, M2), each magnet (M1, M2) preferably comprising a permanent magnetic material or a ferrous magnetic material, the magnetic separation device further comprising an array of sample vessel retaining portions, wherein the first and the second magnetic assembly (3ma, 3mb) of each magnetizing portion are arranged in parallel relation, on opposing sides of and proximate each sample vessel retaining portion and wherein corresponding magnets in the first and the second assembly (3ma, 3mb) are opposed such that the north pole of a magnet in the first magnetic assembly is arranged opposed to the south pole of a magnet in the second magnetic assembly and vice versa. a plurality of magnets (M1, M2) whereby each of the plurality of magnets (M1, M2) has a north pole, a south pole and a magnet axis extending between the north and south poles, and the plurality of magnets (M1, M2) are arranged one above the other in a direction at least substantially perpendicular to the axis of each magnet in such a manner that the north and south poles of adjacent magnets (M1, M2) are arranged alternately and a space is provide between adjacent magnets (M1, M2); and at least one non-magnetic spacing means arranged in the space between adjacent magnets (M1, M2), each magnet (M1, M2) preferably comprising a permanent magnetic material or a ferrous magnetic material, the magnetic separation device further comprising an array of sample vessel retaining portions, wherein the first and the second magnetic assembly (3ma, 3mb) of each magnetizing portion are arranged in parallel relation, on opposing sides of and proximate each sample vessel retaining portion and wherein corresponding magnets in the first and the second assembly (3ma, 3mb) are opposed such that the north pole of a magnet in the first magnetic assembly is arranged opposed to the south pole of a magnet in the second magnetic assembly and vice versa.