A vacuum cleaner (1, 21, 31) comprises an air inlet opening (3), an air outlet opening (6) and a rotatable separator (9) for separating air and airborne particles. The separator (9) comprises at least one air entrance opening (109) located between the air inlet opening (3) and the air outlet opening (6). The vacuum cleaner (1, 21, 31) is provided with air-guide means (15, 22, 37) for guiding at least part of the air towards the separator (9). In use, the air-guide means (15, 22, 37) provides an at least partially closed boundary in axial direction for a column of rotating air (17) around the separator (9). The minimum distance (Rag) of an edge (115, 122) of the air-guide means (15, 22, 37) to the rotating axis (11) of the separator (9) is larger than a distance (Rs) of the air entrance opening (109) of the separator (9) to the rotating axis (11) of the separator (9).