Abstract: An adjustable bed base (1) for supporting a person (22) on a mattress (17) loosely lying on the bed base, comprising a leg part (2) and a back part (3), connected to each other by an adjusting mechanism (4) which comprises a first part (5) connected to the back part (3) and a second part (6) connected to the leg part (2), the first and second parts engaging each other and being movable with respect to each other along a predetermined curve which is determined such that the back part (3) upon movement tilts with respect to the leg part (2) and is simultaneously moved in longitudinal and height directions of the bed base (1).