An adjustably lockable hinge for motor-vehicle seats comprises first and second hinge elements and a pintle between these elements defining a pivot axis therefor. A first arcuate row of equispaced first abutments is carried on the first element spaced from the main axis and facing axially in one direction. A body carrying a second arcuate row of equispaced second abutments facing axially from the body opposite to the one direction and axially aligned with the first row is rotationally linked to the second element. The abutments of the second row are spaced apart by a predetermined distance different from the spacing between the first elements, so that only a limited number of the second abutments can mesh at one time with the first abutments. An adjustment device rotatable about the axis relative to the elements is engageable with the body for precession of the second row on the first row. These rows may be annular arrays of gear-type teeth and the body may be a ring around the hinge pintle.