A seat comprising a seat base portion which is adjustable in respect of inclination has a seat base frame which is mounted pivotally at its rearward portion on a supporting arrangement. Disposed on the supporting arrangement in the front region thereof is a rotary shaft, with a lever arm secured to each end thereof. The lever arms are in turn pivotally connected to the seat base frame. At least one of the lever arms has a plurality of detent openings which are disposed in an arcuate array and which can be selectively engaged by a detent member carried by the seat base frame, to latch the seat base frame in the desired inclined position. The actuating lever for the detent member is disposed at the side of the seat, within easy reach of the occupant thereof.